Network discovery mechanisms

ABSTRACT

In some of the preferred embodiments, a method for network discovery of a mobile device to use at least one of a plurality of access networks within an IP network includes: obtaining specified network information in the vicinity of a given location based on a set of criteria when a mobile is connected to the IP network from any location.

FIELD OF THE INVENTION

The present application relates to, inter alia, methods for networkdiscovery mechanisms, including, e.g., methods for network discoverymechanisms for secure fast handoff and the like. The present applicationclaims priority under 35 U.S.C. 119 to each of the following U.S.Provisional Patent Applications: 1) Ser. No. 60/625,106, filed on Nov.5, 2004, entitled Network Discovery Mechanism For Secure Fast Handoff;2) Ser. No. 60/593,377, filed on Jan. 9, 2005, entitled NetworkDiscovery Mechanisms; 3) Ser. No. 60/670,655, filed on Apr. 13, 2005,entitled Network Discovery Mechanisms; and 4) Ser. No. 60/697,589, filedon Jul. 11, 2005, entitled RDF Schema Update for 802.1 BaselineDocument—the entire disclosures of each of the foregoing fourprovisional patent applications to which priority is claimed areincorporated herein in their entireties. In addition, the entiredisclosures of each of the following co-pending patent applications ofthe present assignee are incorporated herein by reference forbackground: U.S. patent application Ser. No. 10/761,243 entitledMobility Architecture Using Pre-Authentication, Pre-Configuration and/orVirtual Soft-Handoff, filed on Jan. 22, 2004.

BACKGROUND DISCUSSION

Networks and Internet Protocol:

There are many types of computer networks, with the Internet having themost notoriety. The Internet is a worldwide network of computernetworks. Today, the Internet is a public and self-sustaining networkthat is available to many millions of users. The Internet uses a set ofcommunication protocols called TCP/IP (i.e., Transmission ControlProtocol/Internet Protocol) to connect hosts. The Internet has acommunications infrastructure known as the Internet backbone. Access tothe Internet backbone is largely controlled by Internet ServiceProviders (ISPs) that resell access to corporations and individuals.

With respect to IP (Internet Protocol), this is a protocol by which datacan be sent from one device (e.g., a phone, a PDA [Personal DigitalAssistant], a computer, etc.) to another device on a network. There area variety of versions of IP today, including, e.g., IPv4, IPv6, etc.Each host device on the network has at least one IP address that is itsown unique identifier. IP is a connectionless protocol. The connectionbetween end points during a communication is not continuous. When a usersends or receives data or messages, the data or messages are dividedinto components known as packets. Every packet is treated as anindependent unit of data.

In order to standardize the transmission between points over theInternet or the like networks, an OSI (Open Systems Interconnection)model was established. The OSI model separates the communicationsprocesses between two points in a network into seven stacked layers,with each layer adding its own set of functions. Each device handles amessage so that there is a downward flow through each layer at a sendingend point and an upward flow through the layers at a receiving endpoint. The programming and/or hardware that provides the seven layers offunction is typically a combination of device operating systems,application software, TCP/IP and/or other transport and networkprotocols, and other software and hardware.

Typically, the top four layers are used when a message passes from or toa user and the bottom three layers are used when a message passesthrough a device (e.g., an IP host device). An IP host is any device onthe network that is capable of transmitting and receiving IP packets,such as a server, a router or a workstation. Messages destined for someother host are not passed up to the upper layers but are forwarded tothe other host. The layers of the OSI model are listed below. Layer 7(i.e., the application layer) is a layer at which, e.g., communicationpartners are identified, quality of service is identified, userauthentication and privacy are considered, constraints on data syntaxare identified, etc. Layer 6 (i.e., the presentation layer) is a layerthat, e.g., converts incoming and outgoing data from one presentationformat to another, etc. Layer 5 (i.e., the session layer) is a layerthat, e.g., sets up, coordinates, and terminates conversations,exchanges and dialogs between the applications, etc. Layer-4 (i.e., thetransport layer) is a layer that, e.g., manages end-to-end control anderror-checking, etc. Layer-3 (i.e., the network layer) is a layer that,e.g., handles routing and forwarding, etc. Layer-2 (i.e., the data-linklayer) is a layer that, e.g., provides synchronization for the physicallevel, does bit-stuffing and furnishes transmission protocol knowledgeand management, etc. The Institute of Electrical and ElectronicsEngineers (IEEE) sub-divides the data-link layer into two furthersub-layers, the MAC (Media Access Control) layer that controls the datatransfer to and from the physical layer and the LLC (Logical LinkControl) layer that interfaces with the network layer and interpretscommands and performs error recovery. Layer 1 (i.e., the physical layer)is a layer that, e.g., conveys the bit stream through the network at thephysical level. The IEEE sub-divides the physical layer into the PLCP(Physical Layer Convergence Procedure) sub-layer and the PMD (PhysicalMedium Dependent) sub-layer.

Wireless Networks:

Wireless networks can incorporate a variety of types of mobile devices,such as, e.g., cellular and wireless telephones, PCs (personalcomputers), laptop computers, wearable computers, cordless phones,pagers, headsets, printers, PDAs, etc. For example, mobile devices mayinclude digital systems to secure fast wireless transmissions of voiceand/or data. Typical mobile devices include some or all of the followingcomponents: a transceiver (i.e., a transmitter and a receiver,including, e.g., a single chip transceiver with an integratedtransmitter, receiver and, if desired, other functions); an antenna; aprocessor; one or more audio transducers (for example, a speaker or amicrophone as in devices for audio communications); electromagnetic datastorage (such as, e.g., ROM, RAM, digital data storage, etc., such as indevices where data processing is provided); memory; flash memory; a fullchip set or integrated circuit; interfaces (such as, e.g., USB, CODEC,UART, PCM, etc.); and/or the like.

Wireless LANs (WLANs) in which a mobile user can connect to a local areanetwork (LAN) through a wireless connection may be employed for wirelesscommunications. Wireless communications can include, e.g.,communications that propagate via electromagnetic waves, such as light,infrared, radio, microwave. There are a variety of WLAN standards thatcurrently exist, such as, e.g., Bluetooth, IEEE 802.11, and HomeRF.

By way of example, Bluetooth products may be used to provide linksbetween mobile computers, mobile phones, portable handheld devices,personal digital assistants (PDAs), and other mobile devices andconnectivity to the Internet. Bluetooth is a computing andtelecommunications industry specification that details how mobiledevices can easily interconnect with each other and with non-mobiledevices using a short-range wireless connection. Bluetooth creates adigital wireless protocol to address end-user problems arising from theproliferation of various mobile devices that need to keep datasynchronized and consistent from one device to another, thereby allowingequipment from different vendors to work seamlessly together. Bluetoothdevices may be named according to a common naming concept. For example,a Bluetooth device may possess a Bluetooth Device Name (BDN) or a nameassociated with a unique Bluetooth Device Address (BDA). Bluetoothdevices may also participate in an Internet Protocol (IP) network. If aBluetooth device functions on an IP network, it may be provided with anIP address and an IP (network) name. Thus, a Bluetooth Device configuredto participate on an IP network may contain, e.g., a BDN, a BDA, an IPaddress and an IP name. The term “IP name” refers to a namecorresponding to an IP address of an interface.

An IEEE standard, IEEE 802.11, specifies technologies for wireless LANsand devices. Using 802.11, wireless networking may be accomplished witheach single base station supporting several devices. In some examples,devices may come pre-equipped with wireless hardware or a user mayinstall a separate piece of hardware, such as a card, that may includean antenna. By way of example, devices used in 802.11 typically includethree notable elements, whether or not the device is an access point(AP), a mobile station (STA), a bridge, a PCMCIA card or another device:a radio transceiver; an antenna; and a MAC (Media Access Control) layerthat controls packet flow between points in a network.

In addition, Multiple Interface Devices (MIDs) may be utilized in somewireless networks. MIDs may contain two independent network interfaces,such as a Bluetooth interface and an 802.11 interface, thus allowing theMID to participate on two separate networks as well as to interface withBluetooth devices. The MID may have an IP address and a common IP(network) name associated with the IP address.

Wireless network devices may include, but are not limited to Bluetoothdevices, Multiple Interface Devices (MIDs), 802.11x devices (IEEE 802.11devices including, e.g., 802.11a, 802.11b and 802.11g devices), HomeRF(Home Radio Frequency) devices, Wi-Fi (Wireless Fidelity) devices, GPRS(General Packet Radio Service) devices, 3G cellular devices, 2.5Gcellular devices, GSM (Global System for Mobile Communications) devices,EDGE (Enhanced Data for GSM Evolution) devices, TDMA type (Time DivisionMultiple Access) devices, or CDMA type (Code Division Multiple Access)devices, including CDMA2000. Each network device may contain addressesof varying types including but not limited to an IP address, a BluetoothDevice Address, a Bluetooth Common Name, a Bluetooth IP address, aBluetooth IP Common Name, an 802.11 IP Address, an 802.11 IP commonName, or an IEEE MAC address.

Wireless networks can also involve methods and protocols found in, e.g.,Mobile IP (Internet Protocol) systems, in PCS systems, and in othermobile network systems. With respect to Mobile IP, this involves astandard communications protocol created by the Internet EngineeringTask Force (IETF). With Mobile IP, mobile device users can move acrossnetworks while maintaining their IP Address assigned once. See Requestfor Comments (RFC) 3344. NB: RFCs are formal documents of the InternetEngineering Task Force (IETF). Mobile IP enhances Internet Protocol (IP)and adds means to forward Internet traffic to mobile devices whenconnecting outside their home network. Mobile IP assigns each mobilenode a home address on its home network and a care-of-address (CoA) thatidentifies the current location of the device within a network and itssubnets. When a device is moved to a different network, it receives anew care-of address. A mobility agent on the home network can associateeach home address with its care-of address. The mobile node can send thehome agent a binding update each time it changes its care-of addressusing, e.g., Internet Control Message Protocol (ICMP).

In basic IP routing (e.g., outside mobile IP), routing mechanisms relyon the assumptions that each network node always has a constantattachment point to, e.g., the Internet and that each node's IP addressidentifies the network link it is attached to. In this document, theterminology “node” includes a connection point, which can include, e.g.,a redistribution point or an end point for data transmissions, and whichcan recognize, process and/or forward communications to other nodes. Forexample, Internet routers can look at, e.g., an IP address prefix or thelike identifying a device's network. Then, at a network level, routerscan look at, e.g., a set of bits identifying a particular subnet. Then,at a subnet level, routers can look at, e.g., a set of bits identifyinga particular device. With typical mobile IP communications, if a userdisconnects a mobile device from, e.g., the Internet and tries toreconnect it at a new subnet, then the device has to be reconfiguredwith a new IP address, a proper netmask and a default router. Otherwise,routing protocols would not be able to deliver the packets properly.

The preferred embodiments improve upon technologies described, e.g., inthe following references, each of which is incorporated herein byreference in its entirety:

-   [1] Sun Microsystems, Jini Connection Technology.-   [2] Sun Microsystems, Jini Community Resources: Jini Technology    Architectural Overview, January 1999.-   [3] Sun Microsystems, Jini Community Resources: Jini Specification    v1.0.1.-   [4] W. Keith Edwards, Core JINI, The Sun Microsystems Press Java    Series, Prentice Hall, 1999.-   [5] Microsoft Corporation, Universal Plug and Play: Background.-   [6] Microsoft Corporation, Universal Plug and Play Device    Architecture Version 1.0, Jun. 8, 2000.-   [7] Yaron Y. Goland, Ting Cai, Paul Leach, Ye Gu, and Shivaun    Albright, Simple Service Discovery Protocol, IETF Draft    draft-cai-ssdp-v1-03.txt, Oct. 28, 1999.-   [8] Salutation Consortium, Salutation Architecture Specification    Version 2.0c. Part 1, The Salutation Consortium, Jun. 1, 1999.-   [9] Salutation Consortium, Salutation Architecture Specification    Version 2.0c. Part 2, The Salutation Consortium, Jun. 1, 1999.-   [10] Bob Pascoe, .Salutation-Lite: Find-and-Bind Technologies for    Mobile Devices, Salutation.-   Consortium, Jun. 6, 1999.-   [11] Brent Miller, .Mapping Salutation Architecture APIs to    Bluetooth Service Discovery Layer. Bluetooth Consortium 1.C.118/1.0,    Jul. 1, 1999.-   [12] Bob Pascoe, Salutation Architectures and the newly defined    service discovery protocols from Microsoft and Sun, Salutation    Consortium, Jun. 6, 1999.-   [13] Ryan Troll, Automatically Choosing an IP Address in an Ad-Hoc    IPv4 Network, IETF Draft draftietf-dhc-ipv4-autoconfig-05.txt, Mar.    2, 2000.-   [14] Bluetooth Consortium, .Specification of the Bluetooth System    Core Version 1.0 B: Part E, Service Directory Protocol (SDP), Nov.    29, 1999.-   [15] Bluetooth Consortium, Specification of the Bluetooth System    Profiles Version 1.0 B: Part K-2, Service Discovery Application    Profile. Dec. 1, 1999.-   [16] IETF SVRLOC Working Group, Service Location Protocol Home Page.-   [17] E. Guttman, C. Perkins, J. Veizades, and M. Day, .Service    Location Protocol, Version 2,. IETF RFC 2608, June 1999.-   [18] E. Guttman, C. Perkins, and J. Kempf, Service Templates and    Service: Schemes, IETF RFC 2609, June 1999.-   [19] Rekesh John, UPnP, Jini and Salutation, A look at some popular    coordination frameworks for future networked devices, California    Software Labs, Jun. 17, 1999.-   [20] IETF ZEROCONF Working Group, Zero Configuration Networking    (zeroconf).-   [21] INS: Intentional Naming System.-   [22] The Berkeley Service Discovery Service.-   [23] R. Droms, Dynamic Host Configuration Protocol, IETF RFC 2131,    March 1997.-   [24] Sun Microsystems, Java 2 Platform Midcro Edition (J2ME)    Technology for Creating Mobile Devices, White Paper, May 19, 2000.-   [25] World Wide Web Consortium, Extensible Markup Language (XML).-   [26] Marco Liebsch and Ajoy Singh (editors), “Candidate Access    Router Discovery”, Internet Draft    draft-ietf-seamoby-card-protocol-06.txt, Internet Engineering Task    Force, June 2004.-   [27] J. Hodges and R. Morgan, “Lightweight Directory Access Protocol    (v3): Technical Specification”, IETF RFC 3377, September 2002.-   [28] M. Liebsch, A. Singh, H. Chaskar, D. Funato and E. Shim,    “Candidate Access Router Discovery,” Internet-Draft, work in    progress, June 2004.-   [29] K. Arabshian and H. Schulzrinne, “GloServ: Global Service    Discovery Architecture,” First International Conference on Mobile    and Ubiquitous Systems: Networking and Services.

SUMMARY OF THE INVENTION

The present invention improves upon the above and/or other backgroundtechnologies and/or problems therein.

According to some of the preferred embodiments, to, for example, reducedelay and transient data loss in real-time secure roaming/handoff eitherbetween the same types or between heterogeneous access networks,proactive handoff mechanisms such as secure pre-authentication can beused. Pre-authentication involves, for example, performingauthentication with a network before a mobile moves into the network. Toachieve secure pre-authentication with a target neighboring network, amobile should obtain information, e.g., an IP address, from the targetnetwork when the mobile is still outside the target network and thenshould establish a security association with, for example, anauthentication agent in the target network (such as, e.g., a PANAauthentication agent). To do this, the mobile should discover theparameters of various network elements in the target network ahead oftime so that the mobile can communicate with these network elements toestablish proactive security associations. This document describes,among other things, a number of approaches for a mobile to discover thenetwork elements in target networks before moving into these targetnetworks. This document also describes, among other things, how, e.g.,network discovery can help provide fast-handoff using securepre-authentication and proactive IP address acquisition.

According to some embodiments, a method for network discovery of amobile device to use at least one of a plurality of access networkswithin an IP network includes: obtaining specified network informationin the vicinity of a given location based on a set of criteria when amobile is connected to the IP network from any location.

In some examples, the network information includes information used bythe mobile to access the access networks. In some examples, theinformation includes network attachment point identification of anaccess point. In some examples, the information includes a security typesupported by an access point. In some examples, the information includesa layer 3 type. In some examples, the information includes a providername. In some examples, the information includes addresses of servers oragents. In some examples, the information includes addresses ofauthentication agents. In some examples, the information includesaddresses of access routers.

According to some embodiments, a method for the discovery of networkinformation of a target network by a mobile device includes: a)dynamically constructing at least one discovery database of networkinformation; and b) using the at least one discovery database to providenetwork information about the target network before the mobile device isconnected to the target network.

In some examples, the method employs an Application-layer mechanism forInformation Service (AIS). In some examples, the method is used todiscover information used by the mobile device for handoff andpre-authentication. In some examples, the method employs an AIS that islayer 2 independent. In some examples, the method uses network-assisteddiscovery mechanisms. In some examples, the method uses mobile-assisteddiscovery mechanisms. In some examples, the method uses network-assistedmechanisms for constructing the database. In some examples, the methoduses mobile-assisted mechanisms for constructing the database. In someexamples, the mobile queries an AIS server or a peer mobile to obtaininformation regarding networking elements in the target network. In someexamples, the method further includes using reporting agents (RAs) toobtain the information. In some examples, the method further includesusing AAA servers to obtain the information. In some examples, themethod further includes using DNS servers to obtain the information. Insome examples, the method employs a peer-to-peer model in which mobiledevices serve as information servers. In some examples, the methodemploys a scoped multicast approach. In some examples, the methodemploys a recursive broadcast approach.

The above and/or other aspects, features and/or advantages of variousembodiments will be further appreciated in view of the followingdescription in conjunction with the accompanying figures. Variousembodiments can include and/or exclude different aspects, featuresand/or advantages where applicable. In addition, various embodiments cancombine one or more aspect or feature of other embodiments whereapplicable. The descriptions of aspects, features and/or advantages ofparticular embodiments should not be construed as limiting otherembodiments or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present invention are shown by a way ofexample, and not limitation, in the accompanying figures, in which:

FIG. 1 is a view illustrating, among other things, architecture of JiniConnection Technology;

FIG. 2 is a view of an UPnP protocol stack;

FIG. 3 is a view showing a model of the salutation manager;

FIG. 4 is a view showing collaborative discovery of local services andnetwork capabilities;

FIG. 5 is a view showing populating a database using Reporting Agents(RAs);

FIG. 6 is a view showing protocol flow for network service discovery;

FIG. 7 is a view showing an example of geo-coordinate based networkservice discovery;

FIG. 8 is a view showing an example of AP's MAC Address based networkservice discovery;

FIG. 9 is a view showing peer-to-peer-based Network Discovery;

FIG. 10 is a view showing Scoped-based Multicast;

FIG. 11 is a view showing Recursive Broadcast FIG. 12 is a view showingIntegration of Network Discovery and Secure Seamless handoff;

FIG. 13 is a view showing an Example Integrated Flow (NetworkDiscovery+Pre-authentication);

FIG. 14 is a view showing Network Discovery and Pre-auth Flow Diagram;

FIG. 15 is a view showing interaction between different components ofdatabase engines;

FIGS. 16(A)-(C) are views related to a demo system.

FIGS. 17(1)-17(10) are views showing illustrative and non-limiting RDFschema for Network Discovery that uses XML format.

FIGS. 18(1)-18(10) are views showing some illustrative embodiments andaspects related to Service Access Point (SAP) definition and call flow.

FIGS. 19(1)-19(13) are views showing some illustrative embodiments andaspects related to MIH function and Information Services as set forth inAttachment A to the above-listed first provisional application filed onNov. 5, 2005.

FIG. 20 shows a graphical representation of the currently definedRDF/XML schema.

FIGS. 21(1)-21(2) show a basic schema represented in RDF/XML format.

FIGS. 21(3)-21(12) show an extended schema represented in RDF/XMLformat.

FIG. 22 shows an example graphical representation of the 802.21 MIISbasic schema in which ‘Network’ ‘L2’, ‘L3’ ‘Location’ ‘IPv4’, ‘IPv6’,‘Link-Type’, ‘PoA’, “Civic Address’, ‘Geo-Coordinates’ are representedas class, while all others are properties of classes.

DISCUSSION OF THE PREFERRED EMBODIMENTS

While the present invention may be embodied in many different forms, anumber of illustrative embodiments are described herein with theunderstanding that the present disclosure is to be considered asproviding examples of the principles of the invention and that suchexamples are not intended to limit the invention to preferredembodiments described herein and/or illustrated herein.

3 Introduction

In the evolution of wireless networking based on wireless LAN (LocalArea Network) and cellular technologies, and as mobility servicesprevail and people become increasingly mobile, it is more important fora mobile device to be able to find an appropriate point of networkattachment that meets the application requirements and thecharacteristics of the mobile, in a timely, accurate and efficientmanner. We refer to such functionality as network discovery.

The network discovery problem discussed in this document is formalizedas: Obtaining specified network information in the vicinity of a givenlocation based on a set of criteria when a mobile is connected to the IPnetwork from any location. Here,

-   -   Network information can be any information that a mobile uses to        access networks. Such information includes, for example, a        network attachment point identification (e.g., an L2 address        and/or a geographical address of an access point), a MAC type        (e.g., “IEEE 802.11g”) of an access point, a security type        (e.g., “WPA” or “PANA and IPsec”) supported by an access point,        a layer-3 type (e.g., “IPv4 only” or “IPv4/v6 dual stack”), a        provider name, or the addresses of a server or an agent (e.g.,        PANA authentication agents, access routers, SIP servers and        Mobile IP home agents).    -   The location of a mobile or the location which the mobile wants        to find information about may be identified (expressed) in        different ways. For example, it may be identified by the        geographical position, by the identification of the network, or        by the addresses of the wireless access points or IP access        routers in the networks.

The functionality to discover network information can be used to bettersupport mobility and mobile services. For example, to reduceinterruptions to on-going application sessions during a handoff, amobile device could perform pre-authentication with a target networkbefore it starts the handoff into the target network. To do so, themobile will need information about the neighboring networks, such as theaddress of the authentication server in the target network, before themobile moves into the target network. We will refer to the process inwhich a mobile discovers information about its neighboring networks asnetwork neighborhood discovery.

An important problem in network discovery is the discovery databaseconstruction problem: how to construct a database of network informationin an automated, dynamic and efficient way? Solving this problem is nottrivial in a multi-provider environment where a network provider may notbe willing to disclose any network information of its own network toother network providers that compete with it, while it may providedetailed network information of its own network to its subscribers forbetter services. However, there has been no practical solution to solvethis problem.

There are many protocols designed for service discovery (See Section 2).However, none of those protocols provides support for

-   -   Discovering information about neighboring networks    -   Dynamic construction of the discovery databases    -   Determining what information to collect and provide to mobiles.

Instead, the existing service discovery mechanisms focus on how toretrieve information already existing in databases. They rely on alllocal network providers to implement service information servers, whichis too strict to be deployed in public networks.

This document describes a new architecture to support network discoveryincluding methods to solve the discovery database construction problemand methods for mobiles to discover information regarding neighboringnetworks. The proposed architecture is referred to as Application-layermechanisms for Information Service (AIS). AIS is designed to beextensible enough to support current and future types of networkinformation that may be needed by mobiles. AIS leverages existingprotocols as much as possible. Although information about the networkelements can have multiple usages, we focus on discovering theinformation a mobile can use to enable proactive handoff and securedpre-authentication and discuss how these information can be used tosupport secured and proactive handoff.

4 Related Work

Several service discovery protocols and architectures exist todayincluding SLP, JINI, UPnP, Salutation, and LDAP. However, they focusmostly on how a user retrieves service-related information assuming thatthe information is already available in the databases. Theservice-related information and hence the servers used to host theinformation can be organized into a hierarchy, for example, in a waysimilar to the Internet Domain Name System (DNS). The service-relatedinformation can be pre-configured or dynamically on the servers. Theinformation can then be updated either by human administrators orautomatically by servers themselves exchanging updates with each other.

When the network size and the user population grow, pre-configuringinformation to advertise will not be a scalable solution regardless ofwhether service-related information or network information isadvertised. Requiring servers to automatically populate and update thenetwork information also have several limitations, including thefollowing:

-   -   The network information that each mobile device wishes to know        can vary significantly depending on the capabilities and        applications of the mobile device. For example, some mobile        devices may wish to know the addresses of the DHCP server or the        address of the authentication server in a neighboring network so        that the mobile can acquire an IP address from the neighboring        network and perform pre-authentication with the neighboring        network before it needs to handoff into the neighboring network.        Other mobile users may only wish to know the available local        services. It is difficult for a network provider to foresee what        information will be needed by a large number of diversified        current and future users. As result, it is difficult for a        network provider to determine what information to maintain in        the information servers.    -   Mobile users will need to rely on local network providers to        provide the information servers. It is difficult to expect that        all network providers everywhere around the world will provide        such information servers. Furthermore, different network        providers may choose to provide different sets of information.    -   None of the many service discovery protocols available today        seems to be a clear winner that is flexible enough to handle the        diversified and changing services and network information needed        by the mobile users. As a result, different network providers        may use different service discovery protocols. This means that        users may have to use different service discovery protocols in        different networks, which is a heavy burden for users.

Recently, some efforts have been underway to design discovery protocolsthat are specifically used to support network neighborhood discover. Arepresentative example is the Candidate Access Router Discovery (CARD)protocol [28]. A candidate access router is an access router in aneighboring network to which the mobile device may move into. CARD isdesigned to be used by a mobile device to discover a candidate accessrouter, before the mobile performs IP-layer handoff into the neighboringnetwork, in order to support seamless IP-layer handoff. With CARD, amobile listens to layer-2 identifiers such as IEEE 802.11 BSSIDsbroadcast from the radio Access Points (APs) in neighboring networksprior to making a decision about IP-layer handoff. The mobile then sendsthese layer-2 identifiers to the access router in its current network,which will in turn map the layer-2 identifiers the IP addresses of thecandidate access routers in the neighboring network and then send thecandidate router addresses back to the mobile. Using CARD to supportnetwork neighborhood discovery leads to the following limitations:

-   -   CARD requires neighboring access routers to communicate with        each other dynamically to exchange capability information. This        is typically impossible when neighboring networks belong to        different network providers.    -   To discover target access routers, a mobile has to use CARD to        communicate with its current access router. It will be difficult        to expect all access networks around the world to implement        CARD.    -   The information a user can discover using CARD depends on what        information a local network provider configures its CARD        protocol to provide and can vary significantly from network to        network. Furthermore, as discussed above, a network provider may        not provide the right information needed by a mobile because the        network provider cannot easily foresee the diversified and        changing needs of the networking software and applications on        every mobile device.

More recently IEEE 802.11 TGu (Task Group U) has been looking intomethods by which it can provide more upper layer information as part oflayer-2 beacons. This way as the mobile monitors the beacons from theneighboring networks passively; it can determine other layer 3information. But because of the maximum transmission unit size limit allthe layer-3 information may not be accommodated as part of layer-2beacons. It may also be difficult to support multiple heterogeneousaccess technologies. Thus it is important to have a solution that islayer-2 agnostic and can work over multiple heterogeneous access. Aspart of this proposal we have come up with an application-layer networkneighborhood discovery process to find out different parameters such asIP address, QoS (Quality of Service) and security parameters of theneighboring networks.

4.2 Survey of Existing Service Discovery Mechanisms

With the emergence of wireless ad-hoc networks, specialized informationappliances are taking over the technology landscape. These informationappliances have been born to aim at supporting mobility, in essence, andhence cooperation among them, since cooperation is an indispensablefeature that complements some missing parts in mobile device, comparedto conventional, fully-powered computing devices. For this cooperation,several service discovery protocols (SDPs) have been proposed as thepart of coordination architectures that ensure device interaction withthe ultimate aim of simple, seamless and scaleable deviceinter-operability. Among emerging SDPs, Jini, Universal Plug and Play,Salutation, and SLP are conspicuous.

3.3.1 JINI Connection Technology

The purpose of the Jini architecture is to federate groups of devicesand software components into a single, dynamic distributed system [2].Jini systems provide mechanisms for service construction, lookup,communication, and use in a distributed system. Examples of servicesinclude devices such as printers, displays, or disks; software such asapplications or utilities; information such as database and files; andusers of the system.

The heart of the Jini system is a trio of protocols called discovery,join, and lookup [2]. A pair of these protocols, i.e., discovery andjoin, occurs when a device is plugged in. Discovery occurs when aservice is looking for a lookup service with which to register. Joinoccurs when a service has located a lookup service and wishes to joinit. Lookup occurs when a client or user needs to locate and invoke aservice described by its interface type (written in the Java programminglanguage) and possibly, other attributes. The following steps show whatinteractions are needed among a client, a service provider, and a lookupservice for a service to be used by the client in a Jini community [2][1].

1) A service provider locates a lookup service by multicasting a requeston the local network or a remote lookup service known to it in priori.

2) The service provider registers a service object and its serviceattributes with the lookup service. This service object contains Javaprogramming language interface for the service, including the methodsthat users and applications will invoke to execute the service, alongwith any other descriptive attributes.

3) A client requests a service by Java type and, perhaps, other serviceattributes. A copy of the service object is moved to the client and usedby the client to talk to the service.

4) Then, the client interacts directly with the service provider via theservice object.

Jini connection technology consists of an infrastructure and aprogramming model which address the fundamental issues of how devicesconnect with each other to form an impromptu community. Based on Javatechnology as shown in FIG. 1 [1] [2], Jini technology uses Java RemoteMethod Invocation protocols to move code around the network. Networkservices run on top of the Jini software architecture. In this regard,FIG. 1 shows Architecture of Jini Connection Technology.

a. Lookup Service

The lookup service can be viewed as a directory service, in thatservices are found and resolved through it. In a Jini community,services register their proxy objects with a lookup service throughdiscovery and join process, and clients query the lookup service to findout the services they want. Jini uses three related discovery protocols,useful in different situation [3] [4]. Multicast Request Protocol isused when an application or service first becomes active, and needs tofind lookup services in the vicinity. Multicast Announcement Protocol isused by lookup services to announce their presence to the services thatmay have interest in the community. Unicast Discovery Protocol is usedto establish communications with a specific lookup service known to itin priori over a wide-area network.

But a Jini lookup service does much more than a simple name server. Aclient sees a service as an interface, including methods that the clientwill invoke to execute the service, along with any other descriptiveattributes. The lookup service maps interfaces seen by the client to setof service proxy objects. The client downloads the service proxy, whichis actually RMI stub that can communicate back with the server. Thisproxy object enables the client to use the service without knowinganything about it. Hence, there is no need for device driver scenario.Although service proxy object is typical scenario of service invocation,i.e., accessing services through RMI method invocation, the downloadedservice object can be the service itself or a smart object capable ofspeaking any private communication protocol.

b. Leasing

Access to services in the Jini system is granted on lease basis: Aservice is requested for a time period and, then, granted for negotiatedperiod between the service user and provider. This lease must be renewedbefore its expiration. Otherwise, the resources associated with theservices are released. For the example, the lookup service grants leaseto a service registration and the service should continue to renew thelease. A device can leave the community or fail abruptly without havinga chance to deregister itself. So, it is the leasing that enables theJini system to be kept robust and maintenance-free.

c. Remote Events and Transactions

Besides the basic service discovery/join and lookup mechanism, Jinisupports remote events and transactions that help programmers writedistributed programs in reliable and scalable fashion. Remote eventenables an object to be notified when desired change occurs in thesystem. These events can be triggered by newly-published services orsome state changes of services. For example, a Jini palmtop thatregistered its interest in printers can be notified by the lookupservice, when a printer becomes available. Also, Jini supports two-phasecommit (2PC) protocol. By nature, Jini is used to build distributedsystems where reliability and robustness are likely to get impaired bypartial failures and recovery. But Jini 2PC allows flexibility, in thatit does not dictate this protocol to be followed strictly. Rather, it isbeing left to applications (transaction participants) to implementnecessary actions intended by the application logic.

3.3.1 UPnP (Universal Plug and Play)

Universal Plug and Play (UPnP) [6] is architecture for pervasivepeer-to-peer network connectivity of intelligent appliances, wirelessdevices, and PCs of all form factors. Although it's introduced as anextension to the plug and play peripheral model, UPnP is more than asimple extension to it. In UPnP, a device can dynamically join anetwork, obtain an IP address, convey its capabilities upon request, andlearn about the presence and capabilities of other devices. Finally, adevice can leave a network smoothly and automatically without leavingany unwanted state behind [6]. Universal Plug and Play leverages TCP/IPand the Web technologies, including IP, TCP, UDP, HTTP and XML, toenable seamless proximity networking in addition to control and datatransfer among networked devices in the home and office.

UPnP uses Simple Service Discovery Protocol (SSDP) [7] for servicediscovery. This protocol is used for announcing a device's presence toothers as well as discovering other devices or services. Therefore, SSDPis analogous to the trio of protocols in Jini: discovery, join, andlookup. SSDP uses HTTP over multicast and unicast UDP which are referredto as HTTPMU and HTTPU, respectively.

A joining device sends out an advertisement (ssdp:alive) multicastmessage to advertise its services to control points. They are thepotential clients of services embedded into the device. In contrast toJini, there is no central service registry in UPnP. The other message ofSSDP is search (ssdp:discover) multicast message sent when a new controlpoint is added to the network. Any device that hears this multicastshould respond to it with a unicast response message.

XML is used to describe device features and capabilities. Theaforementioned advertisement message contains a URL that points to anXML file in the network, describing the UPnP device's capability. Henceother devices, by retrieving this XML file, can inspect the features ofthis device and decide whether it fits their purposes. This XMLdescription allows complex, powerful description of device capability asopposed to Jini's simple service attribute.

FIG. 2 shows an illustrative UPnP Protocol Stack. For communicationbetween devices, UPnP uses the protocol stack shown in FIG. 2 [6].According to the latest specification [6], UPnP features can beepitomized as the following five steps.

Discovery:

The UPnP discovery protocol is based on SSDP. When a device added to thenetwork, the device advertises its services to the control points on thenetwork. Similarly, when a control point is added to the network, theUPnP allows that control point to search for devices of interest on thenetwork. The fundamental exchange in both cases is a discovery messagecontaining a few, essential specifics about the device or one of itsservices, e.g., its type, identifier, and a pointer to more detailedinformation.

Description:

After a control point has discovered a device, the control point stillknows very little about the device. For the control point to learn moreabout the device and its capabilities, or to interact with the device,the control point must retrieve the device's description from the URLprovided by the device in the discovery message. The UPnP descriptionfor a device is expressed in XML and includes a list of any embeddeddevices or service, as well as URLs for control, eventing, andpresentation.

Control:

After a control point has retrieved a description of the device, thecontrol point can send actions to a device's service. To do this, acontrol point sends a suitable control message to the control URL forthe service. Control messages are also expressed in XML using the SimpleObject Access Protocol (SOAP). Like function calls, in response to thecontrol message, the service returns any action-specific values.

Eventing:

An UPnP description for a service includes a list of actions the serviceresponds to and a list of variables that model the state of the serviceat run time. The service publishes updates when these variables change,and a control point may subscribe to receive this information. Theservice publishes updates by sending event messages. Event messagescontain the names of one of more state variables and the current valueof those variables. These messages are also expressed in XML andformatted using the General Event Notification Architecture (GENA).

Presentation:

If a device has a URL for presentation, then the control point canretrieve a page from this URL, load the page into a browser, anddepending on the capabilities of the page, and allow a user to controlthe device and/or view device status.

Another important feature of UPnP is automatic configuration of IPaddresses being plugged in. Being introduced for this purpose, AutoIP[13] enables a device to join the network without any explicitadministration. When a device is connected to the network, it tries toacquire an IP address from a DHCP server on the network. But in theabsence of a DHCP server, an IP address is claimed automatically from areserved range for the local network use. So, named as AutoIP. Thedevice claims an address by randomly choosing an address in the reservedrange and then making an ARP request to see if anyone else has alreadyclaimed that address.

3.3.1 Salutation

Salutation is another major cooperation architecture, which is beingdeveloped by the Salutation Consortium, to solve the problems of servicediscovery and utilization among a broad set of appliances and equipmentand in an environment of widespread connectivity and mobility. Given thediverse nature of target devices, it is processor, operating system andcommunication protocol independent. The architecture provides a standardmethod for applications, services and devices to describe and toadvertise their capabilities to other applications, services anddevices. The architecture also enables application, services and devicesto search other applications, services or devices for a particularcapability, and to request and establish interoperable sessions withthem to utilize their capabilities [8] [9].

As shown in FIG. 3 [8], the Salutation architecture is composed of twomajor components: Salutation Manager and Transport Manager. TheSalutation Manager is the core of the architecture, similar to thelookup service in Jini. It is defined as a service broker: .A serviceprovider registers its capability with a Salutation Manager. When aclient asks its local Salutation Manager for a service search, thesearch is performed by coordination among Salutation Managers. Then, theclient can use the returned service. . . . A Salutation Manager sits onthe Transport Managers that provide reliable communication channels,regardless of what the underlying network transports are.

The Salutation Manager provides a transport-independent interface toServer and Client applications. This interface (SLM-API) includesservice registration, service discovery, and service access function.

The communication protocol independence of Salutation architecture isachieved by the interface (SLMTI) between Salutation Manager andTransport Manager. Transport Manager is an entity, dependent on thenetwork transport it supports. A Salutation Manager may have more thanone Transport Manager, in case it is attached to multiple, physicallydifferent networks. But Salutation Manager sees its underlying transportthrough the transport-independent interface (SLM-TI).

With reference to FIG. 3, this figure shows a view depicting a Model ofthe Salutation Manager. The main tasks provided by the SalutationManager can be summarized as follows.

Service Registry:

The Salutation Manager contains a registry to keep information aboutServices. A client registers or unregisters itself. All registration isdone with the local Salutation Manager or near one connected to theclient. This is correspondent to the lookup service in Jini.

Service Discovery:

The Salutation Manager discovers other Salutation Managers and servicesregistered there. Remote services are discovered by matching type(s) andset of attributes specified by local Salutation Manager. Thiscommunication protocol between Salutation Managers is called theSalutation Manger Protocol using Sun's ONC RPC. This unique feature,called capability exchange, is needed, because services are basicallyregistered with the local Salutation Manager in the same equipment. Thiscooperation among Salutation Managers forms the conceptually same lookupservice, but distributed over the network, as Jini does.

Service Availability:

A client application can ask the local Salutation Manager toperiodically check the availability of services. This checking is donebetween the local manager and the corresponding manager. This is anarrow version of Jini's Remote Event concept.

Service Session Management:

This session management addresses the service invocation aspect ofSalutation. A service session is established when a client wants to usea service discovered through Service Discovery. The service session isoperated in one of 3 different modes: native mode, emulated mode, andsalutation mode. The Salutation Manager may or may not be involved inmessage exchanges in the service session, depending on the modes. In thenative mode, messages are exchanged through a native protocol andSalutation Manager is never involved in message exchange. In theemulated mode, the Salutation Manager Protocol is used to carry messagesbetween client and service but Salutation Manager doesn't inspect thecontents. In the salutation mode, Salutation Managers not only carrymessages, but also define the message formats to be used in the session.

A Functional Unit is defined as a basic building block in Salutationarchitecture. In other words, it is the minimal meaningful function toconstitute a client or service. A collection of Functional Units definesa Service Record. For example, a fax service can be defined by [Print],[Scan], and [Fax Data Send] Functional Units. Each functional unit iscomposed of descriptive attribute record. These Service/FunctionalUnit/Attribute records are specified with ISO 8824 ASN.1.Salutation-Lite [10] is also worth to mention here. Salutation-Lite is ascaled down version of the Salutation architecture targeted at deviceswith small footprints. The Salutation Consortium envisions thatSalutation-Lite has tremendous applicability to small informationappliances such as palm-size and handheld computers (i.e. Palm and WinCEdevices). Salutation-Lite also lends itself well to low bandwidthnetwork such as IR and Bluetooth.

3.3.1 SLP (Service Location Protocol) and Others

Service Location Discovery (SLP) [17] is an IETF version of servicediscovery protocol but it has unique backgrounds, target areas, andfeatures, as other service discovery protocols do. SLP is adecentralized, lightweight, scale and extensible protocol for servicediscovery within a site [16]. SLP defines Service URL which definesservice type and address for the service. For example,“service:printer:lpr://hostname” s the Service URL for line printerservice available at hostname. Based this Service URL, a user browsesservices available in its site and makes use of selected services tomeet the user's need. For example, a user (application) uses SLP to findout any color printer on the same floor.

There are three agents in SLP: User Agent (UA), Service Agent (SA), andDirectory Agent (DA). UA is a software entity that sends servicediscovery requests on behalf of a user application. SA is an entity thatadvertises service on behalf of a service. As a centralized serviceinformation repository, DA caches advertisements from SAs and,afterwards, responds to requests from UAs. An SA advertises itself byregistering with a DA. This registration message contains the URL forthe advertised service, lifetime for the service, and a set ofdescriptive attributes for the service. The SA should periodicallyrefresh the registration with DA before its expiration. This lifetime ismeant to prevent the network from being left in transient state andsimilar concept is found at other service discovery protocols such asJini and UpnP. A DA caches the registration and sends an acknowledgemessage to the SA. A UA send a service request message to the DA torequest the location of a service. Then, the DA responds with a servicereply message including the URLs of the services matched against the UAneeds. Now, the UA can access the service pointed by the returned URL.In SLP, DA is optional. There may be no DA in small networks. In thiscase the UA's service request message is directly sent to SAs.

SLP supports service browsing and string-based query for serviceattributes which allow UA to select the most appropriate service fromamong services on the network. The UA can request query operators suchas AND, OR, comparators (=, <, <=, >, >=), and substring matching. Thisis more powerful than others. For example, in Jini, service attributematching can be done only against equality.

Finally, SLP is said to be a solution to the intranet service discoveryneeds but it scales well to larger network. The scalability is supportedby various features such as the minimal use of multicast messages, scopeconcept, and multiple DAs.

Bluetooth protocol stack also contains a SDP [14] for service discovery.Since Bluetooth SDP is designed specially for Bluetooth environments, itsupports limited functionality, compared to other service discoveryprotocols. Basically, SDP supports search by service class, search byservice attributes, and service browsing. Service browsing is used whena client has no priori knowledge about services available in theclient's vicinity. Service discovery application profile [15] definesprotocols and procedures used by a service discovery application tolocate services in other devices. Bluetooth SDP runs on a predefinedconnection-oriented channel of L2CAP.

Bluetooth SDP is optimized for Bluetooth devices with limitedcomplexity. Thus, it addresses primarily service discovery problem. Itprovides neither access to services, brokering of service, serviceadvertisement, nor service registration. There's no event notificationwhen services become unavailable. Therefore, other service discoveryprotocol might be used to complement these lacks. For example,Salutation can be used above Bluetooth SDP. Such mapping [11] seems tobe neat because of Salutation's transport-independent architecture.

There are other players in this area: Zero Configuration Networking(zeroconf) [20], MIT's INS (Intentional Naming System) [21], and theBerkeley Service Discovery Service [22]. With a different objective,each of them takes a different approach from others. As a result, theyhave some strong and weak features, relatively compared to otherprotocols.

Recently, efforts have been underway to design discovery protocols tosupport network neighborhood discovery. A representative example is theCandidate Access Router Discovery (CARD) [26] protocol beingstandardized by the IETF. A candidate access router is an access routerin a neighboring network which the mobile device may move into. CARD isa protocol that can be used by a mobile to discover candidate accessrouters before the mobile performs IP-layer handoff into a neighboringnetwork. With CARD, a mobile listens to layer-2 IDs from the radioAccess Points (APs) in neighboring networks prior to making a decisionabout IP-layer handoff. The mobile then uses the CARD protocol to sendthese layer-2 IDs to the access router in its current network, whichwill in turn map the layer-2 IDs to the IP addresses of the candidateaccess routers in the neighboring networks and then send the candidaterouter addresses back to the mobile. CARD has the following limitations:

-   -   It requires that neighboring access routers use the CARD        protocol to dynamically exchange network information, which is        typically impossible when neighboring networks belong to        different network providers. As a result, CARD cannot be used to        support mobility across heterogeneous radio systems, e.g.,        between cellular networks and wireless hot spot networks, which        belong to different network providers.    -   CARD also requires all access routers to implement the CARD        protocol to communicate with mobile users, which is a difficult        proposition.

The information a mobile device can discover via CARD depends on whatinformation each individual local network provider configures its CARDprotocol to provide, which can vary significantly from network tonetwork. The networking capabilities that each mobile device wishes toknow can vary significantly depending on the networking capabilities andapplications of the mobile device and can change over time. It isdifficult for a network provider to foresee what information will beneeded by the mobile devices. For example, a mobile device with theability to perform pre-authentication may wish to know the address ofthe authentication server in a neighboring network so that the mobilecan perform pre-authentication with the neighboring network before itneeds to handoff into the neighboring network. Other mobile devices mayonly want to know, for example, the address of the SIP server/proxy orthe DHCP server in a neighboring network.

LDAP (Lightweight Directory Access Protocol) [LDAP] is a generaldirectory lookup protocol and it allows directory update operation andthus can be used for collecting data from mobiles. However, LDAP is nota suitable solution for the basic network discovery problem because (i)LDAP supports lookup hierarchically constructed databases only, whilestructures for network information databases can be more than trees(i.e., graphs) and (ii) LDAP does not support querying database schemaswhich are likely to change frequently as new networking technologies aredeployed.

3.3.1 Gloserv

Gloserv [29] is a service discovery architecture that provides severaltypes of services that may include event, location-based services,communication and web services. Gloserv architecture is similar to DNSas it contains root name servers and authoritative name servers thatmanage the information services. It can have some high level categoriesfor name servers such as events, services, people or places. Gloservarchitecture provides sets of services such as registration ability toannounce one's services, querying ability with local user agents for acertain set of services from the server. Gloserv uses RDF schema todefine the sets of services and it uses Sesame for creating and storingRDF records. Sesame can use HTTP, Java RMI or SOAP as part of itsquerying mechanism.

AIS-based information discovery mechanisms on the other hand is used todiscover network elements in the neighboring networks that have certaintypes of property such as (QoS, access points, routers, SIP servers,PANA authentication agents) unlike the location-based services such asnearest restaurant, nearest event of certain kind such as concert etcoffered by Gloserv. Information provided by Gloserv service architecturewill not be sufficient to provide enough information to providefast-handoff. AIS-based service discovery scheme uses RDF as thedatabase structure, but uses SOAP, HTTP, XML, WSDL, JENA as accompanyingprotocols to provide proper transport mechanism for database populationby the scouts, reporting agents and information querying by the mobiles.Thus AIS-based service discovery scheme is more suitable for mobileusers who would like to set up secured pre-authentication by discoveringthe network elements such as APs, routers, SIP servers, PANA servers inthe neighboring elements ahead of time which is otherwise out of scopeby other discovery mechanism such as Gloserv.

3.3.1 Comparison Between Existing Service Discovery Mechanisms

Several service discovery protocols are proposed to facilitate dynamiccooperation among devices/services with minimal administration and humanintervention. In order to be able to support the impromptu community,they should provide the means to announce its presence to the network,to discover services in the neighborhood, and to access to services.Basically, all Jini, UPnP, Salutation, and SLP address these aspects,but in different perspectives. A direct comparison must be avoided,since they put different weights on the above functionality.Nevertheless, such comparison is tried here, since it would be helpfulto understand each of them. Table 1 summarizes the features of majorservice discovery protocols.

Jini and UPnP envision pervasive computing environments being enabled bytheir solutions, whereas Salutation and SLP are primarily dealing withthe service discovery problem. Note that Jini provides 2PC transactionand JavaSpace to help develop network services [3]. UPnP's SSDP is justa part of UPnP specification. A good comparison among Jini, UPnP, andSalutation is presented in [19].

Jini has a dependence on Java to enable all its promises. It assumesthat devices support Java Virtual Machine, even though a Jini-proxy canbe used for a cluster of resource-poor devices [3]. Moreover, Jini/RMIis not supported by J2ME CLDC (Connected Limited, Device Configuration)configuration for small information devices such as cell phone, pager,and POS [24].

Jini's service proxy concept is one of strongest features not found atothers. But this no-need-for drivers scenario presumes that the Jinidevices with standard interfaces are already available in the network.It's not as simple as it sounds, since it means all manufactures of acertain device type must consent to the standard interface. First, thestandardizations for printer and storage device interfaces are under wayby the consortia of manufactures.

UPnP relies on the existing IP and Web technology. It seems unique interms of its XML use for service/device description. XML allows forpowerful description of device capability, control command issued to thedevice, event from it. UPnP introduces new features for selfconfiguration which exploit AutoIP and DHCP, but these features are alsofound in IPv6 [19]

The Salutation is well defined but confined to the service discoveryprotocol and session management. Salutation accordingly doesn't addressfeatures like remote event notification, which are no doubt useful indistributed environment. When it comes to transport protocol, IP isgiven top priority by Jini, UPnP/SSDP, and SLP. Salutation can operateover any network layer protocol such as IP and any physical/link layertechnologies including IR and IEEE 802.11 wireless LAN. This transportindependence is the strongest feature of Salutation.

More than one SLP DAs are likely to be deployed for an enterprisenetwork, since a DA becomes the single point of failure. These DAs canbe organized in a hierarchy to provide better performance. Also, theremay be some overlap in their coverage of organization/departments toprovide reliability. This interaction or cooperation between DAs forperformance and reliability is being explored by SLP society. SLPv2 canensure the integrity and authenticity of SLP messages by includingauthentication information in SLP message. It deals with securityproblem directly, while others have to rely on other security protocols.

Comparison Table for Major Service Discovery Protocols and AIS RelatedWork: Jini, SLP, UPnP, Salutation, Gloserv Jini UPnP Salutation SLPGloserv AIS Web Page www.sun. www.upnp.org www.salutation.orgwww/svrloc.org Early stage Ref. Not available yet com/jini MobiquitousMain Entities Lookup Control Point, Salutation Manager, Discovery Agent,Local User Agent AIS Server, Mobile Service, Devices Transport Manager,Service Agent, Service Agent Node (Scouts-MN)) Client, (services) ClientServer User Agent Service Service Lookup No A set of SLMs DA RegistryServer AIS Server Repository Service (Salutation Manager) (DiscoveryAgent) Service Discovery/ Advertisement Registering with Service No NOAnnouncement Join (ssdp:alive) local Salutation registration ProtocolManager Service Query to Contact Query to local SLM Contact DA orDiscover Network Query to AIS Server. Discovery Lookup control andcooperation multicast to SAs Services in the (WSDL/SOAP) Four Servicepoint, or among SLMs current network Architectures listen to 1) End Nodeassisted advertisement 2) Reporting Agent Assisted 3) AAA Assisted 4)Peer-to-Peer Access to Service Invoking Service Session Service typeConnects to a MN directly Service proxy object Action to the Management(service protocol) global server accesses the based on RMI service forthe that can be service if (SOAP), Query discovered service hierarchicalas permitted for variable well state Service Interface Description FU(Functional Service type And Uses XML/RDF Description in XML Descriptiontype and in XML Unit) and attribute format or its variant and Scopingattribute attributes matching (fairly matching within it powerfulmatching) Service Leasing CACHE- No Lifetime in Cache Cache RegistrationCONTROL service Lifetime header in registration alive message ServiceGroup No No Scope No Service accessed Group only by AIS Server's MNEvent Remote Service Availability No Yes No Notification Eventspublishes Checking (periodic event(GENA) and automatic) when statevariable changes Others Java-centric Automatic Transport AuthenticationSuitable for 1) Not dependent on architecture configuration independencesecurity feature discovering specific programming (AutoIP) specific setof environment like JINI services 2) Adopts service description virtuesof SLP and UPnP 3) Easy Deployment 4) Solution can be customized forindividual ISP.5 Description of AIS5.2 Summary of Differences Between AIS and Existing Service DiscoveryMechanisms

Jini, SLP, UPnP, and Salutation are not capable of discovering networkneighborhood information. Gloserv does not describe methods fordiscovering the network elements in the neighboring networks withcertain service parameters.

The following features make our solution unique:

-   -   AIS provides support for discovering information about        neighboring networks in addition to information about the        mobile's currently attached network.    -   It is easy for AIS to determine what information to collect and        how to provide it (existing service discovery protocols focus on        how to retrieve info already existing in databases).    -   No reliance on local network providers to implement service        information servers, which can be an obstacle when deployed in        public networks.    -   AIS is layer 2 independent (independent of CDMA, IEEE 802.11,        GPRS, etc.)    -   AIS includes both network-assisted and mobile-assisted discovery        mechanisms.    -   AIS includes both network-assisted and mobile-assisted        mechanisms for constructing a network information database.        5.3 AIS Architecture

Information construction process, information retrieval methodology,format of the information stored in the information server are some ofthe key design factors that need to be looked into while designing thediscovery architecture.

We have designed several architectures for AIS. They can broadly beclassified into two main categories: network-assisted andmobile-assisted. In the following sections we describe thesearchitectures and how different functional elements can interact witheach other. In each of these architecture alternatives, the mobile willquery an AIS server or a peer mobile to find out the informationregarding the networking elements in the neighboring networks. Themethods of constructing the information database differ in eachdifferent architecture. A network-assisted architecture can follow boththe distributed and centralized model. The AIS server keeps theinformation about the network elements in the neighboring networks andwill provide the information after getting a query from the mobile. In acentralized model, reporting agents in each network will report theinformation about the networking elements within the network by usingSNMP MIB (Simple Network Management Protocol Management InformationBase). The mobile-assisted model is always distributed in nature wherethe end nodes report the information about the networks they arevisiting currently. The way in which the information is retrieved fromthe AIS server by the mobiles is common for both approaches.

Peer-to-peer based model is another mobile-assisted model where themobiles act as the information server and provide the information toother mobiles.

3.3 Information Server-Based Architecture

3.3.1 Discovery Database Construction

Information server-based architecture can be mobile assisted or networkassisted. In the following sections we describe both end-node assistedand network assisted approaches for constructing a network informationdatabase.

3.3.1.1. Mobile-Assisted Approach

We propose a new paradigm for collecting, maintaining, and discoveringlocal services and networking capabilities. The new paradigm willovercome the limitations of the existing approaches described in relatedwork section. The proposed approach uses the following main principles:

-   -   Each mobile user can use any proper means available to him/her        to discover the network information available in a visited        network. Often the user will not need any special assistance        from the visited network solely for the purpose of discovering        the information the subsequent mobiles may need regarding the        visited network. For example, when a mobile connects to a        visited network, it will learn the addresses of the access        routers and authentication agents in the visited network as part        of its normal process for connecting to the visited network.        Such information can be reported to the mobile's AIS server        which can in turn provide the information to subsequent mobiles        before they move into this visited network so that the        subsequent mobiles can retrieve the information. The discovery        of an available hotspot network and its logon requirements also        do not require the local network providers to provide any        special assistance.    -   Each mobile user reports the information it discovers in a        visited network to its AIS server. A mobile's AIS server does        not have to have any trust relationship with the network that        the mobile is currently visiting.    -   A mobile user's AIS server is responsible for maintaining the        information regarding the network information received from its        subscribers regarding different networks.    -   When a subsequent mobile moves into a visited network, it may        query its AIS server for local information it needs.

The proposed approach has the following main advantages over existingapproaches:

-   -   Information mining and discovery will not rely on the local        network providers to provide information servers used to provide        network information.    -   Regardless where a mobile user is and which local network it        currently uses, the mobile always uses a single protocol to        communicate with its AIS server to retrieve network information.    -   An AIS server only needs to maintain information its own        subscribers are interested in.

Furthermore, an AIS server only needs to maintain information regardingthe locations its own subscribers travel to. This allows the proposedparadigm to be highly scalable.

The basic operation of the proposed collaborative discovery paradigm isillustrated in FIG. 4. It shows how mobile moves between the networksand can update the information about the network elements to a locationserver commonly shared by a set of networks. This information is storedin the location server using a specific format. With respect to FIG. 4,the figure shows a view demonstrating collaborative discovery of localservices and network capabilities.

3.3.1.2 Network-Assisted Information Discovery

Network assisted information discovery defines three different methods:These are:

-   -   1. Reporting Agent (RA) assisted;    -   2. AAA assisted;    -   3. DNS-based approach.        3.3.1.2.1 Reporting Agent Assisted

Reporting Agents (RA) are network agents that reside within eachnetwork. These are SNMP capable and have the ability to collect theinformation about the network elements by probing the SNMP MIBs. Thesereporting agents (RA) will collect the information in the respectivedomains and populate the location server database for a specific region.This information may include capability set, IP address, geo-coordinatesof the respective network elements etc. When a specific network elementis attached or becomes operational within a domain, its information ispushed onto the reporting agent (RA), which in turn is sent to the AISserver. Thus, this approach provides a semi-centralized way ofpopulating the AIS server database compared to the end-system assistedapproach described previously. The security concerns are less of anissue here as database update is provided by a specific networking agentinstead of by the end client and there is a preestablished securityassociation between the RA and the information server.

With respect to FIG. 5, the figure shows an example of populating thedatabase using information reported by the Reporting Agents (RAs).

3.3.1.3 AAA Server Assisted

AAA server assisted information building is another network serverassisted approach. Information profile of the mobiles can be saved inthe AAA servers as well. Any AAA protocol such as RADIUS and Diametercan be used for populating the network discovery database in a way thata AAA client sends a pair of an address of the mobile and an address ofthe AAA client to the AAA server. The pair is carried inCalling-Station-Id and Called-Station-Id attributes of the RADIUS andDiameter protocol. The AAA server can collect the information reportedfrom the AAA client and keep track of the mobility pattern of the mobileby recording a list of tuples of (the address of a AAA client, the timethe mobile associated with the AAA client, the time the mobiledisassociated with the AAA client) for the mobile. This list is thenused for constructing the database of neighboring networks among whichmobiles can perform handoff.

It is noted that this approach may not be applicable for multi-providercase where a service provider may not want to disclose its topologicaldatabase to other competing service providers.

3.3.1.4 DNS Server-Based Approach

One can also use DNS SRV record to find out the list of these networkelements instead of using the AIS server. DNS can always populate theservices associated with the network elements (routers, APs) and theirassociated geo-coordinates using DNS's LOC record. Thus one can query aDNS server, give a list of services for a specific domain and the rangeof geo-coordinates and get a list of network elements that provide theseservices. A general query may look like this. Given a set ofgeo-coordinates (R1-R2), find a set of servers that provide a specificset of services such as routing, IEEE 802.11 and AAA. A combination ofDNS “SRV” record and geo-location record will help in determining a setof servers in the vicinity.

Note that this approach is not intended for forming arbitrary structurednetwork information database.

3.3.2 Querying the Discovery Database

Many of the operation such as secured pre-authentication, proactive IPaddress acquisition may be required during a mobile's movement betweendomains, subnets within a domain. These operations which are usuallydone after the mobile has moved to the subnet if done ahead of time willhelp provide the fast-handoff. In order to perform these operation whilein the previous domains/subnets it will need to communicate with thenext hop routers and severs before the movement is over. Thus a mobilewill need to discover the neighborhood information including the APs,routers, DHCP servers and several authentication agents such as PANAauthentication agents and in some cases SIP server before moving to theneighboring networks. This information by means of network discoverywill help a mobile to perform several types of operation ahead of timesuch as pre-authentication and proactive IP address assignment. One suchmechanism is described below that helps a mobile to discover theneighboring network elements. DNS “SRV” mechanism provides anotherapproach of providing the list of such network elements in theneighboring domains.

Initially a mobile boots up, obtains the IP address and configuresitself with other network parameters such as default gateway, andseveral server parameters etc, It begins to communicate with acorresponding host and at certain point during its communication basedon certain policy it determines that the mobile is impending to move.Thus the mobile initiates the AIS process in several different ways. Itcan always use its location information as the look-up key while makinga query. The location information can be the MAC address of an accesspoint, geographic address or any other civic address. When the MACaddress of an access point is used as the look-up key, the mobile canobtain the MAC adders either (i) by listening to beacon frames if themobile is in the radio coverage of the access point or (ii) byrecursively performing the query procedures where the recursion startswith specifying the MAC address of an access point known to the mobilebased on method (i).

The server gets the query and reports back the list of attributes askedbased on the query type. If the client is GPS equipped it can alwaysfinds its own location and determines where it plans to move and thusprovides a range as part of the information look up and obtain thedesired network information.

With respect to FIG. 6, the figure shows a protocol exchange andsequence of operation for the network discovery, query and response.

FIGS. 7 and 8 show scenarios of a client discovering the neighborhoodservers/routers ahead of time, so that it can get the addresses of theneighboring servers and routers where the mobile has the probability ofmoving. The range of geo-coordinates of the mobile and the MAC addressof an access point and are used as the look-up key for querying in FIG.7 and FIG. 8, respectively. Network discovery process will help discoverthe neighborhood servers, routers and access points ahead of time. Bydiscovering the servers ahead of time pre-authentication can beperformed thus expediting the handoff time during the movement. Themobile is currently attached to access point AP0 and has threeneighboring networks D1, D2 and D3 where the mobile has the probabilityto move to. Thus the mobile can query the AIS server with a specific keyand can get the information regarding the neighboring APs, servers, androuters in domains D1, D2 and D3 with which it can communicate with toprepare for the secured handoff. Following paragraph shows a sequence ofoperation after a mobile is booted up.

-   -   1) A mobile boots up and connects to a specific Access Point. It        obtains an IP address via an IP address configuration procedure        through, e.g., DHCP or PPP. The DHCP server or PPP server can        have a range of IP addresses. When geo-coordinates are used as        the look-up key, the range of geo-coordinates is associated with        those IP address and delivered to the mobile together with the        IP address in the IP address configuration procedure. It is        assumed that each and every mobile may not be GPS equipped. If        the mobile knows its own geo-coordinate (R0) and geo-coordinates        are used as the look-up key it could also use its geo-coordinate        as the look-up key. The IP address of the AIS server for a        specific region can be provided by during the IP address        configuration procedure or by using DNS.    -   2) It may also happen that the neighboring cells may belong to        different domains. From DHCP configuration, the mobile can find        out its current domain (e.g., “att.com” or “sprint.com” etc.).        It can also find out the domain names of the neighborhood area        using reverse DNS look up from the IP addresses of the network        elements that were obtained.    -   3) The mobile makes a request to the AIS server using its        currently attached AP and access router such as following:        -   a. The request contains a list of network information types            about which the mobile wants to retrieve (e.g., type=“PANA            authentication server”, “router”) for a specific location            (e.g., geo-location R0 or the MAC address of AP0), with            specifying a condition (e.g., in the Geo-range [R1-R2] or            “within 1 mile”). The condition could be determined based on            the velocity of the mobile or mobility pattern.        -   b. The AIS server returns the list of network information            (e.g., IP addresses of servers and routers, MAC addresses of            APs that satisfies the condition specified in the request by            querying its own database that has been populated            separately.        -   c. From this information I have the list of probable            networks that I am likely to move and thus perform a            time-bound pre-authentication and/or pro-active IP address            acquisition.

With respect to FIG. 7, the figure illustrates an example ofGeo-coordinate based network service discovery, and with respect to FIG.8, the figure illustrates an example of AP's MAC Address based networkservice discovery.

There are additional features for database querying that AIS canprovide. For example, the criteria used for choosing network informationto be provided for a mobile can be either specified by the mobile or bythe AIS server or by both entities. When the AIS server specifies thecriteria, the profile of the mobile may be used as the criteria. In thiscase, the AIS may provide detailed network information for mobilessubscribing to a high-class AIS service than mobiles subscribing to alow-class AIS service.

3.3.3 Peer-to-Peer Model

A peer-to-peer model does not depend upon the information server forinformation storage and retrieval. Instead, each mobile terminal willserve as an information server. We describe two peer-to-peer-basedmodels, such as proactive broadcast and scoped multicast.

In the proposed peer-to-peer model:

-   -   Each mobile moving between the networks keeps the information        about just visited networks in its local cache for a specific        duration;    -   Each neighbor of a mobile will have different information about        the neighboring networks.

The following are two approaches:

-   -   Scoped Multicast Approach        -   Each Scout announces their knowledge of visited networks on            a localized multicast address M, with certain scoping and            the amount of time they will like to keep it in the cache;        -   Based on the proximity of the network and probability of            movement the mobile communicates with the designated peer to            get the particulars of the network.    -   Note: in some examples, a scout may give information itself or        it may point to another scout which has information.    -   Recursive Broadcast Approach        -   Each mobile broadcasts recursively to find the information            about a specific network within the network        -   Broadcast can span beyond its own subnet

With reference to FIG. 9, the figure shows an example of peer-to-peerbased network discovery mechanism. There is no information server inthis architecture, and the mobile can discover about the other networksby querying the peers within the network. This works under theassumption that the mobile carry a lot of information about the othernetworks and keep it in the cache for a specific period of time. Themobile can query this information proactively as it decides to move toother networks and obtains the information about the other networks. Itworks under the assumption that the mobile has the ability tocommunicate with its peers and extract this information. In some casesthere may be a need to establish some sort of security associationbetween the mobile and its peers.

With respect to FIG. 10, the figure illustrates a Scope-based Multicastsystem. On the other hand, with respect to FIG. 11, the figureillustrates a Recursive Broadcast system.

3.3.4 Applicability to Secure Pre-authentication

Network discovery mechanism described here can help all these kinds ofhandovers between different access networks, including, e.g., thefollowing scenarios:

-   -   Handover between 802.11 and 802.3 networks;    -   Handover between 802.3 and 802.16 networks;    -   Handover between 802.11 and 802.16 networks;    -   Handover between 802.11 and 802.11 networks, across ESSs;    -   Handover between 802.3 and Cellular networks;    -   Handover between 802.11 and Cellular networks; and/or    -   Handover between 802.16 and Cellular networks.

In the preferred embodiments, the discovery approach will be applicableto both heterogeneous and homogeneous handoff scenarios.

-   -   Movement among homogeneous Systems        -   Single interface e.g., 802.11, between ESS)        -   Multi interface (e.g., 802.11, between ESS)    -   Movement among heterogeneous networking systems is always dual        mode        -   802.3, 802.11        -   802.11, CDMA/GSM (Cellular)        -   Between Cellular Networks (CDMA, GSM)        -   802.11, 802.16, 802.20        -   802.11, Circuit-switched

The following section discusses a specific scenario to illustrate hownetwork discovery can be integrated to help proactive handoff andsecured pre-authentication mechanism. FIG. 12 shows the diagram showingthe linking between two states, namely discovery of neighboring networksand seamless handoff. In particular, FIG. 12 shows integration ofnetwork discovery and secure seamless handoff.

Integration with Pre-authentication Mechanism:

With respect to FIG. 13, the figure shows: an Example Integrated Flow(Network Discovery+Pre-authentication).

As the mobile moves between the networks, the process of proactivehandoff will primarily include two stages. First stage involvesdiscovering the neighboring elements such as the next hop router, DHCPserver, PANA authentication agent and AAA server in the network themobile is about to move and second stage involves setting up a securedpre-authentication based security association with the PANAauthentication agent in the neighboring network. During this securedpre-authentication the mobile can also obtain an address from the DHCPserver in the next subnet (this does not mean running DHCP over multi-IPhops). By having a secured pre-authentication, the mobile will not needto spend time in setting up security association after moving to the newsubnet. By having an IP address of the next subnet locally available,the mobile may also avoid the time spent for getting an address usingstandard DHCP process, although it may use DHCP INFORM to obtain allother configuration parameters. By having an IP address locallyavailable time taken due to DHCP process is avoided including the ARPchecking.

3.4 Network Discovery Process

This database can be centralized, distributed or peer-to-peer. We areformulating several ways of populating this database. This databasestructure will be, e.g., in RDF format. The mobile will use SOAP/HTTPmechanism to query a certain type of network element that provides aspecific service from the database. As an example a mobile can make aquery to get the list of network elements providing routing service orPANA service in the subnet where a specific access point is connected.The specific access point can be identified by its MAC address. Theremay be other types of information such as quality of the layer-2 link,protection capability, roaming agreement that can act like indexes. In acentralized database model we have planned to use three differentapproaches, such as Reporting Agent-based, AAA-based and end-systembased. In reporting agent-based approach, each reporting agent can useSNMP MIB to populate the required information in the centralizeddatabase in a specific format. Since AAA client in each domain hasaccess to the mobile and the AAA server, it can very well populate thedatabase server with required information. End-system assisted approachtakes advantage of the knowledge built up during a mobile's movementamong the networks. As the mobile moves from one network to another itcollects the information about the networking elements and report to thecentralized database. In a peer-to-peer model there is no centralizeddatabase, but each mobile keeps the list of network elements it has justrecently visited for a specific period of time and publish theircapability and knowledge in a scoped-based multicast. A mobile in acertain network can query this capability and communicate with thespecific neighbor that has the required information.

Secured pre-authentication involves establishing a security associationbetween the mobile and PANA server in the next subnet and obtaining theIP address from the next subnet. FIG. 13 shows the protocol interactionbetween various elements during the transition between the accessnetworks. The mobile makes a move from access network A to accessnetwork B. Access networks A and B can be in two differentadministrative domains. Initially the mobile MN has an address IP0assigned to it. As it is about to move, it passively listens to severalbeacons from the neighboring APs. These beacons of the APs contain theMAC addresses of the APs in the neighboring networks. The mobile usesthe MAC address of the access point as the identifier to discover thenetwork elements in the neighboring access networks. This is achieved byusing an application layer protocol such as SOAP and HTTP that interactswith the AIS server to determine the IP addresses of the networkelements that the mobile would usually interact after it moves to one ofthe neighboring access networks or the target access network. Thesenetwork elements include access routers, PANA authentication agents inthe neighboring network. In order to perform a secured handoff themobile sends a PANA message to the PANA authentication agent that isusually co-located with the Target Access Router (TAR) in theneighboring access network. At this point IKE signaling takes place toset up an IPsec tunnel between the TAR and the mobile. This tunnel isset up to make sure that the data is tunneled through and is secured. Aspart of setting up the tunnel it obtains an IP address from the DHCPserver that is resident in the target access network. The DHCP serverwill dispense an IP address (say IP1) from its IP address pool. The DHCPserver may like to perform an ARP before handing out the IP address tothe mobile through IKEv2 where the TAR acts as a proxy DHCP client forthe mobile. This IP address passed to the TAR through DHCP is thencarried in a Configuration Payload of IKEv2 and finally is assigned tothe mobile as the IPsec tunnel inner address. The mobile now has two IPaddresses, i.e., IP0 and IP1. When the IPsec tunnel is implemented inthe mobile as a logical tunnel interface (i.e., ipsec0) and the mobilehas two addresses, i.e., IP0 for the physical interface (i.e., eth0) andIP1 for the logical tunnel interface. At this time the mobile sends abinding update to the correspondent host (CH) or to the home agent. CHor home agent sends the new data to the mobile's new IP address IP1. Newdata from the CH destined to IP1 will be captured by the TAR and will betunneled via the IPsec tunnel just established. Now as the mobilecrosses over and connects to the new access point AP2, it gets an eventtrigger that will break the old IPsec tunnel and will assign the newaddress IP1 to its physical interface (i.e., eth0).

Since the mobile has obtained the IP address only that can be assignedlocally, as the mobile moves to new network it may perform a DHCP INFORMso as to be able to configure other server parameters such as DNSserver, DHCP server etc. As another option, the parameters may have beenobtained through the IKEv2 signaling for establishing the IPsec tunnelbetween the mobile and TAR before the mobile moves to the target accessnetwork. Another option will be to obtain the parameter through AIS andstore them in the mobile's cache.

Thus when the mobile is in the previous subnet and the tunnel is set upit has two addresses assigned such as:

eth0: IP0;

Ipsec0:IP1 (tunnel interface).

Where as IP0 is the address in the current network, IP1 is the addressfrom the neighboring network.

Note: when the IPsec tunnel is NOT implemented in the mobile as alogical tunnel interface, IP1 would be bind to IPsec SAD (SecurityAssociation Database).

After the mobile moves to the target access network it will have anaddress assignment as follows:

eth0:IP1.

Thus, we use a local process to configure the IP address IP1 to theinterface eth0.

Considerations:

Based on the present disclosure, those in the art can implement a systemtaking into consideration, among other things:

-   -   1. The kind of triggering mechanism that is needed as the mobile        moves into the target access network;    -   2. How to dis-associate the existing tunnel as the mobile moves        into the target access network    -   3. How to take care of PANA authentication over multi-IP hops;        -   a) Modify PANA to run over multi-IP hops;        -   b) Run PANA over an unprotected IP tunnel;    -   4. When the mobile should start the network discovery process,        as it is about to change network;    -   5. How to assign the IPsec tunnel inner address dynamically        using DHCP (detailed interaction between DHCP server and IPsec        gateway must be defined).

With respect to FIG. 14, the figure shows the flow chart of differentmodules associated with a mobile. FIG. 14 depicts a network discoveryand pre-authentication flow diagram. In some embodiments, networkdiscovery and pre-authentication can be effectively used for a mobilethat has multiple interfaces in the following way:

-   -   The mobile always actives only one of the multiple interfaces.        Other interfaces are deactivated for the purpose of, e.g.,        battery saving. Depending on radio conditions and/or other        criteria, the mobile switches from one interface to another,        which requires dynamically discovering layer-2 attachment points        for deactivated interfaces to which the mobile may switch from        the activated interface.    -   Since the deactivated interfaces cannot be used for discovering        their layer-2 attachment points, the AIS procedure to discover        those attachment points is performed through the currently        activated interface. Information on higher-layer network        elements that are associated with those attachment points is        also discovered in the AIS procedure.    -   Once those attachment points and associated higher-layer network        elements are discovered, the mobile is able to perform        pre-authentication procedure for a deactivated interface through        the activated interface in order to establish a security        association between the mobile and the layer-2 attachment point        and pre-configuring the required configuration parameters such        as an IP address before activating the deactivated interface.    -   When the deactivated interface is activated, the bootstrapping        procedure for activating the interface will be faster since most        of the required bootstrapping procedure has been completed        before activating the interface.

Another usage of network discovery for a mobile that has multipleinterfaces is described as follows.

-   -   The mobile has a wireless LAN interface and a cellular        interface. It always activates the cellular interface and has IP        connectivity through the cellular interface. The wireless LAN        interface may always be activated or may be activated on demand        by the user of the mobile.    -   When the wireless LAN interface finds (an) access point(s). It        can perform AIS procedure through the cellular interface to        obtain detailed information about the network connected through        the access point(s). The obtained information can be used by the        mobile to choose an access point to connect.        4. Schema Design

AIS provide a framework that uses the existing standards for accesspoints and routers without the need to make any changes in the routersand access points. Our database schema will use XML, RDF and SOAP. RDFdatabase can be constructed in a distributed fashion to be able to scaleto large number of networks. RDF can also handle arbitraryinterconnected data structure while LDAP handles tree-based datastructure only. RDF can provide querying schema as well as datathemselves.

FIG. 15 shows different components of the network discovery andinteraction between the components. In particular, FIG. 15 showsinteraction between different components of a database engines.

With reference to FIGS. 17(1) to 17(10), an illustrative RDF schema isillustrated for Network Discovery that uses XML format.

5. Demo Scenario

In this section, illustrative network assumptions and a demo scenarioare described. The following merely depicts some illustrative andnon-limiting test examples.

-   -   Network Assumption    -   Create four different Subnets (assume four different networks);    -   Associate four different Edge Routers (ER);    -   Four different Access Points (APs);    -   Four different PANA servers (may coexist with the routers);    -   Define a Mobility Server;    -   Each Network Element has a specific Geo-coordinate associated        with it.

Populating Database on the Mobility Server:

-   -   Have an SNMP query agent (RA) in each network;    -   Each RA queries the network elements and pushes these        information to the mobility server (S):        -   Mobility server keeps a database in a specific format:            -   According to the network;            -   Service Type;            -   Geo coordinate range [r1,h1];        -   Alternatively, the database can be populated by a mobile            visited previously in these networks.

Querying the Database on the Mobility Server:

-   -   Mobile gets powered on, gets an address from DHCP server;    -   Finds out its own position (r0,h0) from DHCP server;    -   Updates it to DNS;    -   Learns the mobility server address from the DHCP or        pre-provisioned;    -   Makes a query with a certain type of service and provide a        range;    -   Gets a list of servers, and make a time bound Pre-authentication        with each of the server as it is about to move;    -   Fast-handoff will be performed accordingly.

With respect to FIGS. 16(A)-(C), these figures demonstrate such anillustrative Demo Setup implemented within a demo lab.

6. Conclusions

This disclosure presents, by way of example, among other things, a fewarchitectures and an application layer scheme for the network discoveryprocess. The disclosure also describes, inter alia, how these techniquescan help provide proactive secured handoff during a mobile's movementbetween heterogeneous access networks.

MIH Function Under 802.21:

The primary role of the MIH Function is to facilitate handoffs andprovide intelligence to the network selector entiity or the mobilitymanagement entity responsible for handover decision as described byother standards or proprietary implementations. The MIH Function aidsthe network selector entity with the help of Event service, Commandservice and Information service. The network selector entity and thehandover policies that control handovers are outside the scope of MIHFunction. Description of specific handover policies and the details ofnetwork selector entity are outside the scope of 802.21 standards aswell.

The IEEE 802.21 specification defines services that enhance handoversbetween heterogeneous access links. This is achieved throughfacilitating handover process by providing link layer intelligencerelevant in handover detection, handover initiation and candidate linkselection by MIH user.

-   -   A Media Independent Event Service (MIES) which provides event        classification, event filtering and event reporting        corresponding to dynamic changes in link characteristics, link        status, and link quality.    -   A Media independent Command Service (MICS) which enables MIH        user to manage and control link behavior relevant to handovers        and mobility.    -   Media Independent Information Service (MIIS) which provides        details on the characteristics and services provided by the        serving and surrounding networks. The information enables        effective system access and effective handover decisions.    -   The above services are supported by the Media Independent        Handover Function (MIHF) to facilitate a MIH user in mobility        management and handover process. The MIH Function provides        convergence of link-layer state information from multiple        heterogeneous access technologies into a unified presentation to        the upper layers of the mobility-management protocol stack.

The 802.21 draft specification is based on, among other things, thefollowing general design principles.

-   -   The Media Independent Handover (MIH) Function is logically        defined as a shim layer in the mobility-management protocol        stack of both the mobile node and the network elements that        provide mobility support. MIH is a helper and facilitator        function which helps in handover decision making. Upper layers        make handover decisions and link selection based on inputs and        context from MIH. Facilitating the recognition that a handover        should take place is one of the key goals of MIH Function.        Discovery of information on how to make effective handover        decisions is also a key component.    -   MIH Function provides abstracted services to higher layers. From        that perspective MIH offers a unified interface to the upper        layers. The service primitives exposed by this unified interface        are independent of the technology specific protocol entities of        the different access networks. The MIH Function communicates        with the lower layers of the mobility-management protocol stack        through technology-specific interfaces. The specification of the        MIH interfaces with the lower layers generally does not fall        within the scope of 802.21. Such interfaces are already        specified as service access points (SAPs) within the standards        that pertain to the respective access technologies, such as IEEE        802.1, IEEE 802.3, IEEE 802.11, IEEE 802.16, 3GPP and 3GPP2.

Media Independent Information Service (MIIS) provides a framework andcorresponding mechanisms by which a MIHF (Media Independent HandoverFunction) entity can discover and obtain network information existingwithin a geographical area to facilitate the handovers. MIIS primarilyprovides a set of information elements (IEs), the information structureand its representation and a query/response type of mechanism forinformation transfer. This contrasts with the asynchronous push model ofinformation transfer for the event service. The information may bestored within the MIH functional (MIHF) entity or maybe present in someinformation server from where the MIH in the station can access it.

The information can be made available via both lower as well as higherlayers. Information can be made available at L2 through both a secureand an insecure port. The structure and definition of a schema can berepresented in a high level language such as XML.

The Information service also provides access to static information suchas neighbor reports. This information helps in network discovery. Theservice may also provide access to dynamic information which mayoptimize link layer connectivity with different networks. This couldinclude link layer parameters such as channel information, MACaddresses, security information, etc. Information about available higherlayer services in a network may also help in more effective handoverdecision making before the mobile terminal actually attaches to anyparticular network.

The Media Independent Information service specifies a common (or mediaindependent) way of representing this information across differenttechnologies by using a standardized format such as XML or ASN.1

MIIS provides the ability to access this information about allheterogeneous networks in a geographical area from any single L2network, depending on how the 802.21 MIIS service is implemented. MIISeither relies on existing access media specific transports and securitymechanisms or L3 transport and L3 security mechanisms to provide accessto the information. Typically, in a heterogeneous network composed ofmultiple media types, it is the handover decision module or higher layermobility management will collect information from different media typesand assemble a consolidated view to facilitate its inter-media handoverdecision.

Some networks such as the cellular networks already have an existingmeans of detecting a list of neighborhood base stations within thevicinity of an area via the broadcast control channel. Other IEEE groupsdefine similar means and supports clients in detecting a list ofneighborhood access points within the vicinity of an area via eitherbeaconing or via broadcast of MAC management messages. The MediaIndependent Information Service (MIIS) provides a unified framework tohelp the higher layer mobility protocols (HLMP) across the heterogeneousnetwork environment to facilitate the client's discovery and selectionof multiple types of networks existing within a geographical area. Inthe larger scope, the macro objective is to help the higher layermobility protocol to acquire a global view of the heterogeneous networksto facilitate seamless handover when roaming across these networks.

Service Access Point (SAP) Definition and Call Flow:

With reference to FIGS. 18(1) to 18(12), these figures show someillustrative embodiments and aspects related to Service Access Point(SAP) definition and call flow. In this regard, FIGS. 18(1) to 18(12)include a plurality of figures depicting the following:

-   -   a) Media Independent Handover (MIH) flow of operation (FIG.        18(1));    -   b) MIH functional model with SAP (FIG. 18(2));    -   c) Local Triggers from Lower Layer (lower SAP)(FIG. 18(3));    -   d) Functional Primitives to/from lower layer (lower SAP)(FIG.        18(4));    -   e) Function Primitives to/from higher layer (higher SAP)(FIG.        18(5));    -   f) Remote Functional Primitives (to and from network)(FIG.        18(6));    -   g) 802.X to 802.X (single I/F) Handover Call Flow (FIGS. 18(7)        to 18(8));    -   h) Cellular/802.Y to/from 802.X Handover Call Flow (FIGS. 18(9)        to 18(10));    -   i) Mapping Between MIH Function and 3GPP Primitives (FIG.        18(11)); and    -   j) Mapping Between MIH Function and 802.11 Primitives (FIG.        18(12)).

Various features and aspects of the embodiments depicted in FIGS. 18(1)to 18(12), as well as various potential modifications and/oradaptations, would be appreciated and understood by those of ordinaryskill in the art based on this disclosure. See also IEEE 802.21 MEDIAINDEPENDENT HANDOVER, DCN: 21-04-0170-00-0000, Title: IEEE 802.21 MediaIndependent Handover Solution Proposal, apparently submitted Nov. 8,2004, Yogesh Bhatt, Ajoy Singh, Nat Natarajan, Madjid Nakhjiri, AlistairBultar, Lach Hong-Yon, the entire disclosure of which is incorporatedherein by reference as though recited herein in full. See also IEEE802.21 MEDIA INDEPENDENT HANDOVER, DCN: 21-04-0171-01-0000, Title:Initial Proposal to IEEE 802.21 from SAMSUNG, apparently submitted Nov.17, 2004, Xiaoyu Liu, Youn-Hee Han, Vivek Gupta, Soo-Hong Park, SungjinLee, Hyungkyu Lim, Chihyun Park, Chongwon Kim, the entire disclosure ofwhich is incorporated herein by reference.

Illustrative Proposal for MIH Function and Information Services:

FIGS. 19(1)-19(13) are views showing some illustrative embodiments andaspects related to Media Independent Handover (MIH) function andInformation Services as set forth in Attachment A to the above-listedprovisional application filed on Nov. 5, 2005. In this regard,information therefrom is incorporated below.

Proposal Scope:

-   -   FIGS. 19(1)-19(13) relate to a partial proposal according to        802.21 requirements document.    -   Covers two important functions:        -   MIH function; and        -   Information Service.    -   Describes specific handover scenarios.

Proposal Outline:

-   -   Bootstrapping Issues:        -   When the device starts up.            -   May depend on how many interfaces the device has.    -   MIH function:        -   Generic MIH Primitives.        -   Primitives for secure and seamless handover and their            mapping with upper layers.        -   Secure handover solution.    -   Information Service:        -   Discovery, detection and selection:            -   Information that the device needs for handover                optimization.        -   Information service model.

Assumptions and Scenarios:

-   -   Assumptions:        -   Multiple radio interfaces for heterogeneous networks.        -   Single or multi(11 a/b/g) interface for homogeneous            networks.    -   Scenarios addressed in this example:        -   802.11 to cellular.        -   802.11 to 802.3/WiMAX.        -   802.11 to 802.11.

Single Radio Interface Scenario:

-   -   A mobile node with a single IEEE 802.xx interface may roam among        multiple subnets and multiple administrative domains.        -   MIH based on information obtained via L2 only has            limitations.        -   MIH might need information from higher layers.            -   Efficient inter-subnet and inter-domain handoff                possible.

Single Radio Interface Roaming Scenario:

With reference to FIG. 19(1), a single radio interface roaming scenariois depicted.

Multiple Radio Interface Scenario:

-   -   A mobile node with multiple interfaces may want to deactivate        unused interfaces.    -   As the mobile node moves, a deactivated interface may need to be        activated depending on the radio conditions.        -   Deactivated interfaces themselves cannot discover their            access points/base stations.        -   Information service that depends upon only on deactivated            interface has some limitations.    -   MIH may further consider deactivated interfaces as candidates to        switch from the currently activated interface.        -   Fast interface activation may become a requirement for MIH.

Multiple Radio Interface Roaming Scenario:

With reference to FIG. 19(2), a multiple radio interface roamingscenario is depicted.

Bootstrapping Scenarios, Issues and Requirements:

Bootstrapping Scenario:

-   -   Device is powered up and interfaces are detecting network        presence    -   Two distinct cases:        -   Device is booting up for the first time in a visited            network.        -   Device is re-booting.            -   Had connection before (a-priori knowledge of the                network).    -   Presence of multiple providers:        -   Similar networks (e.g., only WLAN networks).        -   Dissimilar networks (e.g., WLAN, 3G).

Some Bootstrapping Issues:

-   -   Device may have limited information about the network unless        access is authorized.    -   Device may not have any prior knowledge of the visited network.    -   Multiple networks may not have coverage in a particular region.    -   Device may not have higher layer information unless it is cached        or pre-configured.    -   Device may not have proper security parameters to attach to a        network.

Bootstrapping Solution Requirements:

-   -   Architecture components should address bootstrapping separately.    -   Pros and cons of each proposal should be evaluated based on        security requirements.

Capability of an Example of the Current Solution:

-   -   An example of the proposed solution does not address the        bootstrapping issues.

MIH functions:

-   -   Network Discovery.    -   Security.    -   Mobility/Handover.    -   Quality of Service.    -   Power Management.    -   Other.

Generic MIH Functional Model:

A generic MIH Functional Model is shown in FIG. 19(3).

MIH Functional Model (Information Service, Mobility and Security):

An MIH Functional Model (Information Service, Mobility and Security) isshown in FIG. 19(4).

Generic MIH Primitives:

-   -   Network Discovery primitives:        -   Network name.        -   IP address (network elements, DNS, SIP servers . . . ,            location).        -   Network/Link type.        -   Bandwidth.        -   Cost of using the network.    -   Security Primitives:        -   Security capabilities.        -   Security parameters (keys, SAs, . . . ).        -   Access privilege.    -   QoS primitives:        -   Link type.        -   QoS levels/mappings.        -   Bandwidth.    -   Mobility/Handover Management:        -   Mobility features supported.            -   Protocols, velocity, real-time non-real-time, . . .        -   Handover type.            -   Soft handoff, hard handoff, . . .    -   Power Management.        -   Sleep time, Wake time, . . .        -   Power budget.

MIH Flow of Operation:

An MIH Flow of Operation is shown in FIG. 19(5).

MIH Functions: An Example:

-   -   Network Discovery.        -   getNetworkName( ).        -   getIPaddress ( ).        -   gettypeof server( ).        -   getBandwidth( ).    -   Security.        -   getkeyinformation( ).        -   getsecurityprotocol( ).        -   getauthenticationserver( ).

Secure and Seamless Handover Solution:

-   -   The solution is based upon the concept of Pre-Authentication        (PA) and can be, e.g., defined as:        -   Mobile-assisted authentication scheme that obtains higher            layer information a-priori to performing authentication and            authorization before session and service handovers    -   MIH function performs this process on behalf of mobile users

MIH Pre-Authentication (MPA):

-   -   MIH Pre-Authentication.        -   Provides a secure and seamless mobility optimization that            works for:            -   Inter-subnet handoff.            -   Inter-domain handoff.            -   Inter-technology handoff.                -   Use of multiple interfaces.        -   Defines a new mechanism at higher layer (e.g., Network).            -   Supports IP address change (unlike Layer 2 (L2)                pre-authentication where MAC address does not change).

Functional Components of MPA:

-   -   1) Pre-authentication        -   Used for establishing a security association (SA) between            the mobile and a network to which the mobile may move.        -   L2 pre-authentication can also be enabled based on the            established SA.    -   2) Pre-authorization        -   Used for establishing contexts specific to the network to            which the mobile will move.        -   The SA created in (1) are used to secure the authorization            procedure.    -   3) Virtual Soft Handoff (VSH)        -   Used for sending/receiving IP packets based on the            pre-authorized contexts by using the contexts of the current            network.

Expected Result:

A figure depicting an illustrative expected result according to someembodiments is shown in FIG. 19(6).

Pre-Authentication:

FIG. 19(7) is a schematic diagram illustrating pre-authentication insome illustrative embodiments.

Pre-Authorization:

FIG. 19(8) is a schematic diagram illustrating pre-authorization in someillustrative embodiments.

Virtual Soft Handoff (VSH): Initiation Phase:

FIG. 19(9) is a schematic diagram illustrating an initial phase of avirtual soft handoff in some illustrative embodiments.

VSH: Tunneling Phase:

FIG. 19(10) is a schematic diagram illustrating a tunneling phase of avirtual soft handoff in some illustrative embodiments.

VSH: Completion Phase:

FIG. 19(11) is a schematic diagram illustrating a completion phase of avirtual soft handoff in some illustrative embodiments.

Information Service:

What is Information Service?

-   -   Information service can be defined, e.g., as:        -   Network Discovery:            -   Process by which device collects the information about                the network(s).        -   Network Detection:            -   Process by which device attaches the network and collect                the information.        -   Network Selection:            -   Process by which device selects appropriate network                (e.g., from the information collected by discovery and                detection).

Information Service Solution:

-   -   Application-layer mechanisms for Information Service (AIS).        -   Network discovery is defined using XML-based technologies.        -   Flexible way of retrieving L2 and L3 topological            information.

Application-Layer Mechanisms for Information Service (AIS):

-   -   An application-layer protocol that helps provide information        about the networking elements of the neighboring networks.    -   The information can consist of parameters about networking        elements of various layers, e.g.:        -   access point's MAC address, access router's IP address,            security model, QoS.    -   The information can be queried with using location information        as a look-up key.        -   Location information can be access point identifier,            geographical address, civic address, etc.    -   The information will augment MIH Pre-Authentication (MPA).    -   Provides a link-layer agnostic solution.    -   Provides the ability to move between the administrative domains.    -   Provides a framework that uses the existing standards for access        point and routers without making any changes.    -   Provides a modular and flexible database using XML, RDF, SOAP        -   RDF database can be constructed in a distributed fashion to            scale to large number of networks.        -   RDF can handle arbitrary interconnected data structure while            LDAP handles tree-based data structure only.        -   RDF provides querying schema as well as data themselves.            -   Network information can frequently change its data                structure as networking technologies evolve.        -   Two basic approaches for construction of information service            database:        -   Network-assisted database construction model.        -   Mobile-assisted database construction model.

AIS Comparison with L2 Information Service:

-   -   Information service at L2 is needed for initial network        attachment where no IP connectivity is available at the        beginning.    -   Information service at L2 has some limitations.        -   If information is broadcast in beacons, it consumes a lot of            bandwidth.        -   The mobile needs to be in radio coverage of APs that provide            information service.            -   A mobile moving at a high velocity may need the                information before entering the radio coverage of the                network.            -   A multi-interface mobile may want to discover APs for a                deactivated interface through the active interface.        -   Difficult to handle large-sized data due to lack of            fragmentation in some link-2 protocols (e.g., 802.3).    -   AIS can overcome such limitations.

AIS-aided Secured Seamless Handoff:

-   -   Secured seamless handoff with MPA is based on the information        retrieved from the neighboring networking elements such as:        -   routers, SIP servers, PANA authentication agents, etc.

See also FIG. 12 which depicts an integration of network discovery andsecure seamless handoff.

Information Query Example:

See FIG. 12 which depicts an illustrative information query example.

RDF Schema for AIS (partial view):

FIG. 19(12) shows an illustrative Graphical View of the Schema.

RDF Schema for AIS (detailed view):

FIG. 19(13) shows an illustrative detailed Graphical View of the Schema.

Handover Scenarios:

-   -   Handover from 802.11 to Cellular networks.    -   Handover from 802.11 to 802.11 networks.    -   Handover from 802.11 to 802.3 networks.        Introduction to Information Service Schema:

A schema defines structure of information. A schema is used in the802.21 information service to define the structure of each informationelement as well as the relationship among different information elementssupported. The 802.21 information service schema needs to be supportedby every MIH Function that implements the MIIS to support flexible andefficient information queries. The 802.21 information service definesthe various information elements and their structure. The various IEsrepresent information about lower layers of network stack as well asabout higher layer services available in different access networks. Aschema is defined by a language and can be represented in multiple ways.Examples include Resource Description Framework (RDF) which is based on,e.g., XML, ASN.1 which is used in 802 MlBs, Variants or a simple TLVrepresentation of different information elements.

The MIIS schema is classified into two major categories. Basic schemathat is essential for every MIH to support and Extended schema that isoptional and can be vendor specific.

RDF Schema Representation:

This section gives an example of schema using Resource DescriptionFramework (RDF). See 3GPP TS 23.234, “3GPP system to Wireless Local AreaNetwork (WLAN) inter-working; System description” (Reference [8]). RDFuses SPARQL (see 3GPP TS 23.060, “General Packet Radio Service (GPRS);Service Description; Stage 2” (Reference [7])) as a query language forquerying information. Both RDF schema and SPARQL are represented in XML.An RDF schema defines the structure of set of expressions, where theunderlying structure of any expression is a collection of triples, eachconsisting of a subject, a predicate and an object. XML syntax for RDFcalled RDF/XML is defined in GPP TR 43.901 “Feasibility Study on GenericAccess to A/Gb Interface” (Reference [9]).

RDF has, e.g., the following advantages:

-   -   Supports both hierarchical and non-hierarchical information        structure.    -   Allows for flexible data query    -   Allows for distributed schema definition    -   Easier way to change the schema definition

As discussed below, the RDF schema definition for MIIS has two parts:the basic and the extended schema. The basic schema is not supposed tobe updated. An MIH entity is typically pre-provisioned with the basicschema for ease of implementation of schema-based query. In scenarioswhere the basic schema is not pre-provisioned methods such as DNS querymay be used to access the location (FQDN) of the basic schema.

Unlike the basic schema, the extended schema is expected to be updatedperiodically, e.g., when a new link-layer technology is introduced. Theextended schema can be retrieved from the specified URL via the IEEE802.21 information service using the schema query capability describedin Section 8.5.3 of IEEE 802.21 Media Independent HandoverServices21-05-xxxx-00-0000-One_Proposal_Draft_Text without anypre-provision of such extended schema. The URL of the extended schemacan also be obtained via the schema URL query capability described insaid section 8.5.3. Alternatively, a DNS query may be used for findingout the location (FQDN part) of extended schema. The extended schema isdefined as an extension of the basic schema and includes data structureand relationship of media-specific or higher-layer information. In thatsense extended schema is the complement of basic schema.

Support for RDF/XML Schema in IEEE 802.21 Information Service:

1. Introduction

This section of this document contains (1) RDF/XML schema definition forIEEE 802.21 information service, (2) required changes to the informationservice primitives described in Reference [1] (attached to said priorityprovisional application filed on Apr. 13, 2005) to support RDF/XML basedIEEE 802.21 information service and (3) example usage of the primitivesusing RDF/XML based IEEE 802.21 information service.

2. RDF/XML Schema Definition for IEEE 802.21 Information Service

The RDF/XML schema definition for IEEE 802.21 information service hastwo parts, i.e., the basic schema and the extended schema. Every MIHentity must be pre-provisioned with the basic schema. The basic schemais not supposed to be updated. The rest of the RDF/XML schema is theextended schema. Unlike the basic schema, the extended schema issupposed to be updated, e.g., when a new link-layer technology isintroduced, and an MIH entity does not need to be pre-provisioned withthe extended schema. Instead, the extended schema can be retrieved viathe information service using, e.g., the schema query capabilitydescribed in part 3 below.

FIG. 20 shows a graphical representation of the currently definedRDF/XML schema.

2.1. The Basic Schema

The basic schema is represented in RDF/XML format as shown in FIGS.21(1)-21(2).

2.2. The Extended Schema

An extended schema is represented in RDF/XML format as shown in FIGS.21(3)-21(12).

3. Information Service Primitives Supporting RDF/XML Schema

In [1], two primitives are defined for IEEE 802.21 information service,i.e., MIH_information.request and MIH_information.response as follows.

MIH_Information.request ( InfoQueryFilter, InfoQueryParameters, QueryID) Valid Name Type Range Description InfoQueryFilter Combination of N/A Aset of query QueryFilterType filters which flags control the type andamount of information that is retrieved. InfoQueryParameters N/A Queryfilter specific parameters which indicate the type of information theclient may be interested in. QueryId Integer N/A A unique QueryId tohelp match requests with responses.

MIH_Information.response ( InfoQueryFilter, MIH_REPORT, QueryID, status) Valid Name Type Range Description InfoQueryFilter Combination of N/A Aset of query QueryFilterType filters which flags control the type andamount of information that is retrieved. MIH_REPORT N/A Reportconsisting of information requested by the L3MP or MIH QueryId IntegerN/A Used to match response with requests Status Success/Failure N/ASpecifies whether the information was successfully retrieved or not.

To support information service based on RDF/XML schema, the followingchanges are made to the information service primitives.

3.1. Neighbor Graph Query

A new InfoQueryFilter type “FILTER_INFO_NEIGHBOR_NETWORKS” is defined.When this InfoQueryFilter type is specified, the InfoQueryParametersmust be a string which contains a SPARQL query [2] where the SPARQLquery is supposed to contain an appropriate query for obtaining aneighbor graph. The MIH_REPORT of the correspondingMIH_information.response must be a string which contains a SPARQL queryresult [3].

An example query request and response when FILTER_INFO_NEIGHBOR_NETWORKSis specified as InfoQueryFilter is shown below.

MIH_Information.request (FILTER_INFO_NEIGHBOR_NETWORKS, “PREFIX ndext:<http://www.networkdiscovery.org/2005/04/rdf-extended-schema/> SELECT?z1 WHERE (?x1 ndext:802.11-neighboring-bssid ?z1) (?x1ndext:802.11-bssid, “12:34:56:78:9a:bc”)”, 123)MIH_Information.response(FILTER_INFO_NEIGHBOR_NETWORKS, “<?xmlversion=“1.0”?> <sparqlxmlns=“http://www.w3.org/2001/sw/DataAccess/rf1/result”> <head><variable name=“802.11-neighboring-bssid”/> </head> <results> <result><802.11-neighboring-bssid>aa:bb:cc:dd:ee:ff</802.11-neighboring-bssid></result> <result><802.11-neighboring-bssid>00:11:22:33:44:55</802.11-neighboring-bssid><result> </result><802.11-neighboring-bssid>01:23:45:67:89:ab</802.11-neighboring-bssid><result> </results> </sparql>”, 123)3.2 General RDF/XML Data Query

A new InfoQueryFilter type “FILTER_INFO_DATA” is defined. When thisInfoQueryFilter type is specified, the InfoQueryParameters must be astring which contains a SPARQL query [2] where the SPARQL query issupposed to contain an appropriate query for obtaining expected RDF/XMLdata. The MIH_REPORT of the corresponding MIH_information.response mustbe a string which contains a SPARQL query result [3].

An example query request and response when FILTER_INFO_DATA is specifiedas InfoQueryFilter is shown below.

MIH_Information.request (FILTER_INFO_DATA, “PREFIXndext:<http://www/networkdiscovery.org/2005/04/rdf-extended-schema/>SELECT ?z WHERE (?x, ndext:dhcp_server_address, ?z) (?xndext:router_address, 12.34.56.1)”, 123)MIH_Information.response(FILTER_INFO_DATA “<?xml version=“1.0”?> <sparqlxmlns=“http://www.w3.org/2001/sw/DataAccess/rf1/result”> <head><variable name=“dhcp_server_address”/> </head> <results> <result><dhcp_server_address>12.34.56.78</dhcp_server_address> </result></results> </sparql>”, 123)3.3 RDF/XML Schema URL Query

A new InfoQueryFilter type “FILTER_INFO_SCHEMA_URL” is defined. Whenthis InfoQueryFilter type is specified, the InfoQueryParameters must bea null string. The MIH_REPORT of the correspondingMIH_information.response must be a string which contains a URL for theextended schema. It is left to the implementation how to retrieve theextended schema from the obtained URL.

An example query request and response when FILTER_INFO_SCHEMA_URL isspecified as InfoQueryFilter is shown below.

MIH_Information.request(FILTER_INFO_SCHEMA_URL, “”, 123)

MIH_Information.response(FILTER_INFO_SCHEMA_URL,“http://www.networkdiscovery.org/2005/04/rdf-extended-schema/”,123)

3.4 RDF/XML Schema Query

A new InfoQueryFilter type “FILTER_INFO_SCHEMA” is defined. When thisInfoQueryFilter type is specified, the InfoQueryParameters must be astring which contains an XML-formatted RDF subject in question andoptionally an integer that specifies the depth of the search in theschema graph. The default depth value is zero (0) which represents thatthere is no limit in the depth of the search. When a depth parameter isspecified in addition to an RDF subject parameter, a comma (“,”) is usedas the delimiter of the two parameters. The MIH_REPORT of thecorresponding MIH_information.response must be a string which containsthe obtained RDF/XML schema.

An example query request and response when FILTER_INFO_SCHEMA isspecified as InfoQueryFilter is shown below.

MIH_Information.request(FILTER_INFO_SCHEMA, “<rdfs:Classrdf:about=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/Network”>,0”,123) MIH_Information.response(FILTER_INFO_SCHEMA, “<rdf:RDFxml:lang=“en” xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#”xmlns:rdfs=“http://www.w3.org/2000/01/rdf-schema#”xmlns:nd=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/”><rdfs:Classrdf:about=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/Network”><rdfs:subClassOfrdf:resource=“http://www.w3.org/2000/01/rdf-schema#Resource”/></rdfs:Class> <rdfs:Classrdf:about=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/L2info”><rdfs:subClassOfrdf:resource=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/Network”/> </rdfs:Class> .... <rdfs:Classrdf:about=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/IPv4”><rdfs:subClassOfrdf:resource=“http://www.networkdiscovery.org/2005/04/rdf-schema/L3info”/></rdfs:Class> <rdfs:Classrdf:about=“http://www.networkdiscovery.org/2005/04/rdf-basic-schema/IPv6”><rdfs:subClassOfrdf:resource=“http://www.networkdiscovery.org/2005/04/rdf-schema/L3info”/></rdfs:Class> </rdf:RDF>”,123)4. References

The following references are incorporated herein by reference in theirentireties.

-   [1] “MEDIA INDEPENDENT HANDOVER”,    21-05-0240-01-0000-Joint_MIH_Proposal_Draft_Text-07 (see Appendix A    of the above-listed priority provisional application filed on Apr.    13, 2005, incorporated herein by reference in its entirety).-   [2] “SPARQL Query Language for RDF”,    http://wwww.w3.org/TR/rdf-sparql-query/.-   [3] “SPARQL Variable Binding Results XML Foramt”,    http://www.w3.org/TR/2004/WD-rdf-sparql-XMLres-20041221/.    RDF Schema Update for 802.21 Baseline Document:    1. Introduction

This section of this application contains proposed changes in the RDFSchema defined in 21-05-0271-00-0000-One_Proposal_Draft_Text (802.21baseline document), see the above-referenced provisional patentapplication filed on Jul. 11, 2005 at APPENDIX A.

The RDF schema in the baseline document defines classes and propertiesand relationships among them. However, detailed data types as well ascardinalities are missing in each property. Without defining this levelof details, it is likely that properties used by the 802.21 informationservice are encoded differently by different realizations.

The present section of this application, among other things, definesdetailed data types as well as cardinalities for each property of the802.21 basic schema and an extended schema by using OWL (Web OntologyLanguage) which is defined in World Wide Web Consortium together withRDF and RDF schema.

“In order to strictly define each information element in an RDF schema,the schema is augmented with Web Ontology language (OWL) [14].

OWL is a Web Ontology language. OWL uses both URIs (Uniform ResourceIdentifiers) for naming and the description framework provided by RDF(Resource Description Framework) to add the following capabilities toontologies:

-   -   Ability to be distributed across many systems    -   Scalability    -   Compatibility with other Web standards for accessibility and        internationalization    -   Openess and extensiblility

OWL builds on RDF and RDF Schema and adds more vocabulary for describingproperties and classes: among others, relations between classes (e.g.disjointness), cardinality (e.g. “exactly one”), equality, richer typingof properties, characteristics of properties (e.g. symmetry), andenumerated classes.”

FIG. 22 shows an example graphical representation of the 802.21 MIISbasic schema in which ‘Network’ ‘L2”, ‘L3’ ‘Location’ ‘IPv4’, ‘IPv6’,‘Link-Type’, ‘PoA’, “Civic Address’, ‘Geo-Coordinates’ are representedas class, while all others are properties of classes. The lines indicateeither the range or domain of a property or a sub class of a class. Inparticular ‘r’ represents the range of a property and ‘d’ representsdomain of a property. ‘Domain’ defines the class that a particularproperty belongs to and ‘range’ defines a type of a particular property.A distinct instance of ‘Network’ class is allocated for each PoA.

BROAD SCOPE OF THE INVENTION

While illustrative embodiments of the invention have been describedherein, the present invention is not limited to the various preferredembodiments described herein, but includes any and all embodimentshaving equivalent elements, modifications, omissions, combinations(e.g., of aspects across various embodiments), adaptations and/oralterations as would be appreciated by those in the art based on thepresent disclosure. The limitations in the claims (e.g., including thatto be later added) are to be interpreted broadly based on the languageemployed in the claims and not limited to examples described in thepresent specification or during the prosecution of the application,which examples are to be construed as non-exclusive. For example, in thepresent disclosure, the term “preferably” is non-exclusive and means“preferably, but not limited to.” In this disclosure and during theprosecution of this application, means-plus-function orstep-plus-function limitations will only be employed where for aspecific claim limitation all of the following conditions are present inthat limitation: a) “means for” or “step for” is expressly recited; b) acorresponding function is expressly recited; and c) structure, materialor acts that support that structure are not recited. In this disclosureand during the prosecution of this application, the terminology “presentinvention” or “invention” may be used as a reference to one or moreaspect within the present disclosure. The language present invention orinvention should not be improperly interpreted as an identification ofcriticality, should not be improperly interpreted as applying across allaspects or embodiments (i.e., it should be understood that the presentinvention has a number of aspects and embodiments), and should not beimproperly interpreted as limiting the scope of the application orclaims. In this disclosure and during the prosecution of thisapplication, the terminology “embodiment” can be used to describe anyaspect, feature, process or step, any combination thereof, and/or anyportion thereof, etc. In some examples, various embodiments may includeoverlapping features. In this disclosure, the following abbreviatedterminology may be employed: “e.g.” which means “for example;” and “NB”which means “note well.”

What is claimed is:
 1. A method for network discovery of a mobile deviceto use at least one of a plurality of access networks within an IPnetwork, comprising: said mobile device querying specified networkinformation in the vicinity of a specific location based on a condition;and providing the mobile device with network information in the vicinityof said specific location, wherein said network information satisfiesthe condition specified by the querying; wherein said specific locationis based on a geo-coordinate of said mobile device or an address of anaccess point, and wherein said condition is a distance condition basedon a range of geo-coordinates of the mobile device, said range ofgeo-coordinates being based on the velocity or mobility pattern of themobile device.
 2. The method of claim 1, further including: a)dynamically populating at least one discovery database of networkinformation of an information server; and b) transmitting networkinformation about a target network from said at least one discoverydatabase to the mobile device before the mobile device is connected tothe target network responsive to said querying from the mobile device;further including using resource description framework (RDF) as adatabase structure; further including using said method to discoverinformation used by the mobile device for handoff andpre-authentication.
 3. The method of claim 2, further includingportioning media independent information service schema into basicschema and extended schema categories, wherein basic schema is essentialfor a media independent handover to support and extended schema isoptional for a media independent handover to support.
 4. The method ofclaim 2, wherein said method uses network-assisted discovery mechanisms.5. The method of claim 2, wherein said method uses mobile-assisteddiscovery mechanisms.
 6. The method of claim 2, wherein said method usesnetwork-assisted mechanisms for constructing said database.
 7. Themethod of claim 2, wherein said method uses mobile-assisted mechanismsfor constructing said database.
 8. The method of claim 2, wherein themobile queries an AIS server or a peer mobile to obtain informationregarding networking elements in the target network.
 9. The method ofclaim 8, further including using reporting agents (RAs) to obtain theinformation.
 10. The method of claim 8, further including using AAAservers to obtain the information.
 11. The method of claim 8, furtherincluding using DNS servers to obtain the information.
 12. The method ofclaim 8, wherein the method employs a peer-to-peer model in which mobiledevices serve as information servers.
 13. The method of claim 12,wherein the method employs a scoped multicast approach.
 14. The methodof claim 12, wherein the method employs a recursive broadcast approach.15. The method of claim 1, further comprising: employing anapplication-layer mechanism within an information server for aninformation services (AIS) based service discovery scheme using resourcedescription framework (RDF) as a database structure to maintaininformation regarding a plurality of locations or networks; and saidapplication layer mechanism providing network information from theinformation to said mobile device based on said querying from the mobilenode; and further including setting up a secured pre-authentication fora user by discovering network elements in neighboring elements ahead oftime; and further including discovering one or more of the followingnetwork elements ahead of time: Access Points, routers, SIP servers, andPANA servers.
 16. The method of claim 15, further including using SOAP,HTTP, XML, WSDL and/or JENA as accompanying protocols to provide propertransport mechanism for database population by the scouts, reportingagents and/or information querying by the mobiles.
 17. The method ofclaim 1, further including: providing an information server employing aninformation database that portions media independent information serviceschema into basic schema and extended schema categories, wherein basicschema is essential for a media independent handover to support andextended schema is optional for a media independent handover to support;and transmitting the basic schema or the extended schema to said mobilenode based on said query from the mobile node, wherein the basic schemaor the extended schema pertains to a plurality of networks or locations.18. The method of claim 17, further including providing vendor specificextended schema.
 19. The method of claim 1, wherein said networkinformation includes information used by the mobile device to accesssaid access networks.
 20. The method of claim 1, wherein said networkinformation includes network attachment point identification of anaccess point.
 21. The method of claim 19, wherein said informationincludes layer 3 type information.
 22. The method of claim 19, whereinsaid information includes a security type supported by an access point.23. The method of claim 19, wherein said information includes a providername.
 24. The method of claim 19, wherein said information includesaddresses of servers or agents.
 25. The method of claim 19, wherein saidinformation includes addresses of authentication agents.
 26. The methodof claim 19, wherein said information includes addresses of accessrouters.
 27. A method for network discovery for a mobile device to useat least one of a plurality of access networks within an IP networkprior to handover, comprising: said mobile device querying for specifiednetwork information, said specified network information includinginformation used by the mobile device to pre-authenticate with an accessnetwork prior to handover and pertaining to a specific location within aradio coverage of an access point, and said specified networkinformation being based on a condition specified by the querying; andproviding the mobile device with network information pertaining to saidspecific location within the radio coverage of an access point, whereinsaid network information satisfies the condition specified by thequerying; wherein said specific location is based on a geo-coordinate ofsaid mobile device or an address of an access point, and wherein saidcondition includes a distance condition based on a range ofgeo-coordinates of the mobile device, said range of geo-coordinatesbeing based on the velocity or mobility pattern of the mobile device.28. The method of claim 27, wherein said specific location issubstantially smaller than and inside the radio coverage of an accesspoint.
 29. The method of claim 27, wherein said specific location isidentified based on specific geo-coordinates.
 30. The method of claim28, wherein said specific geo-coordinates are determined based on a GPSsystem.
 31. The method of claim 27, wherein said specific location isidentified based on an address.
 32. The method of claim 31, wherein saidaddress is a MAC address, a geographic address or a civic address. 33.The method of claim 32, wherein said address is a MAC address of anaccess point.
 34. The method of claim 27, wherein said conditionincludes a network information type condition.